24 - extended Gomory cut separator to separate and certify numerically safe MIR cuts
25 - adjusted all primal heuristics (except for five dedicated MINLP heuristics)
26- new interfaces to exact LP solvers SoPlex and QSopt_ex
27
28### Symmetry Handling
29- added more techniques to handle reflection symmetries, in particular, for orbitopes with column reflections and matrices whose rows and columns can be permuted by a symmetry
30- Dejavu can be used to compute symmetries; the source code is shipped with SCIP and incorporates sassy
31- implemented symmetry detection callbacks for disjunction and superindicator constraint handlers
32- detailed information about applied symmetry handling techniques can be printed to the terminal
33- improve memory usage by introducing different constraint handlers for full orbitopes and packing/partitioning orbitopes
34- symmetry detection no longer treats implicit integer variables separately, but computes symmetries based on the variable type inferred from variable bounds and implied integrality
35- extended the statistics to also include information about the number of variables (per type) affected by symmetry
36- implemented method to compute new permutations from a given list of symmetry group generators
37- cons_orbisack, cons_orbitope_full, cons_orbitope_pp, and cons_symresack now try to replace the stored aggregated variables by active ones at the end of presolving;
38 this should reduce the size of copies of the presolved problem
39- simplified symmetry detection graphs in case all edges have the same color
40
41### Presolve
42- distinguish implicit integrality of variables into strong and weak type, depending on whether integrality is implied for all feasible or only at least one optimal solution
43- added a new presolver "implint", which detects implied integral variables by detecting (transposed) network submatrices in the problem; for now, this plugin is disabled by default
44- added support for (transposed) network matrix detection
45- allow multi-aggregation of unbounded slack variables, which may enable more bound tightening due to a reduction in the number of unbounded variables
46- resolve all fixings in xor constraints also for an available integer variable
47
48### Conflict Analysis
49- added generalized resolution conflict analysis that operates directly on linear constraints instead of conflict graphs
50- disabled dualsol and dualray conflict upgrades to maintain conflict store
51- apply general conflict upgrades in conflict store
52
53### Cutting Planes
54- added a new separator "flower" to generate flower cuts from AND constraints and nonlinear product expressions
55- added functionality to deal with hypergraphs by means of efficient access to vertices, edges, and intersections edges
56
57### Primal Heuristics
58- added decomposition kernel search (DKS) heuristic (disabled by default), which implements a kernel search framework;
59 it can be used both as a construction heuristic as well as an improvement heuristic; existing decomposition information can be utilized
60- reduced maximal fraction of diving LP iterations relative to total node LP iterations
61
62### Branching
63- added a dynamic max-lookahead criterion for strong branching; a probability distribution is fitted to the observed candidate gains and
64 evaluating further candidates stops when the expected tree-size reduction no longer justifies the LP evaluation cost
65- added new fields in history to store ancestral pseudo cost updates, used in the pseudo costs branching rule to compute discounted pseudo costs
66
67### Nonlinearity
68- added an interface to the NLP solver CONOPT
69- implemented columnwise Jacobian sparsity computation in the NLP oracle
73- added the possibility to search for irreducible infeasible subsystems (IIS)
74- added new plugin type for finding irreducible infeasible subsystems (IIS)
75- new iisfinder plugin "greedy", which implements a greedy addition and deletion based algorithm with dynamic batch sizing
76
77### Benders' Decomposition
78- when solving a problem with additional decomposition information (for example, when reading a DEC file) and enabling decomposition/applybenders,
79 the problem is now solved in a Benders' decomposition relaxator; instead of decomposing the original SCIP instance, the relaxator builds the decomposed problem in
80 sub-SCIPs and solves it via default Benders' Decomposition; a solution to the original (undecomposed) problem is now made available by the relaxator;
81 the SCIP shell dialog "display statistics" now also prints the statistics from solving the Benders' decomposition in the relaxator
82- adds objective types for Benders' decomposition; the choices are to sum the subproblems objectives (classical approach) and to use the maximum of the subproblems objectives
83- the linking master variables for each Benders' decomposition subproblem are now stored; these can be accessed for the generation of cuts and setting up the subproblems
84
85### Reading and Writing
86- added a new data structure SCIP_DATATREE that holds serializable data and a function to export to a JSON file
87- added ability to collect statistics from tables in a SCIP_DATATREE and write out as JSON file;
88 dialog write statistics now writes a JSON file if name of file to write ends with .json
89- added writing support for AMPL NL writer: currently only general and specialized linear and nonlinear constraints can be written
90- added support for AND-constraints to GAMS writer
91- simplify expressions of nonlinear constraints in MPS and LP writing to increase chance that they are recognized as quadratic
92
93### Applications
94- New application "PBSolver" to solve pseudoboolean instances in OPB and WBO format while complying with PB competition rules
95- Coloring: new parameter branching/coloring/strategy to choose the least/most fractional variable for branching
96
97### Miscellaneous
98- do not allow non-root restarts when no global fixings were found
99- reimplemented SCIPvarGetActiveRepresentatives() by using dense arrays to avoid repeated resorting
100- avoid unnecessary calls of constraint handlers components, benders, benderslp, propagator genvbounds, and heuristics ofins, subnlp, nlpdiving, indicator
101- inlined SCIPgetStatus() to reduce computational overhead
102- variable data pointer are now copied if no copy routine was supplied
103- add check that parameter value pointers are unique, i.e., no two are the same
104
105Interface changes
106-----------------
107
108### Deprecations
109
110- The variable type \ref SCIP_VARTYPE_IMPLINT is deprecated in favor of a new enum \ref SCIP_IMPLINTTYPE that indicates if a
111 variable is implied integral, independent of the variable type.
112 The problem variable arrays is still sorted as:
116 where the implied integral subsection is now subdivided into 3 parts (left to right):
117 ```
118 | binary implied integral | integer implied integral | continuous implied integral |
119 ```
120 SCIP 10 still supports using `SCIP_VARTYPE_IMPLINT` for backward compatibility, see SCIPcreateVar() and SCIPchgVarType() for more details.
121 SCIP 11 will remove `SCIP_VARTYPE_IMPLINT`.
122- SCIPsubversion() is deprecated and will be removed
123
124### New and changed callbacks
125
126- added SCIP_DECL_IISFINDERCOPY(), SCIP_DECL_IISFINDERFREE(), and SCIP_DECL_IISFINDEREXEC() for iisfinder implementations
127- added a new callback SCIP_DECL_TABLECOLLECT() for the table plugin that collects the data for the specific statistics table in a SCIP_DATATREE object
128- for a table plugin, only one of the callbacks SCIP_DECL_TABLECOLLECT() or SCIP_DECL_TABLEOUTPUT() needs to be implemented, but implementing both is preferred;
129 if SCIP_DECL_TABLEOUTPUT() is omitted, then SCIP tries to print a table from the data given by SCIP_DECL_TABLECOLLECT()
130- the callback SCIP_DECL_EXPRINTEGRALITY(), which returns the integrality of an expression, had its fourth argument changed from `SCIP_Bool*` to `SCIP_IMPLINTTYPE*` to represent implied integrality in nonlinear expressions,
131 that is, an implied integral type of an auxiliary variable if the expression were assigned to it
132- added argument `filename` to the SCIP_DECL_READERWRITE() callback in the 4th position
133- the callback SCIP_DECL_READERWRITE() is equipped with `objoffset`, `objscale`, `objoffsetexact`, and `objscaleexact` as arguments 9 through 12 to write the exact objective offset and scale in exact mode
134
135### Deleted and changed API functions
136
137- SCIPgetProbvarLinearSum(): remove parameter `mergemultiples`, which is now automatically true with the new implementation of SCIPvarGetActiveRepresentatives()
138- `SCIPcreateRow*()`, SCIPaddVarToRow(), SCIPaddVarsToRow(), SCIPaddVarsToRowSameCoef() can now only be called in the solving stage, because otherwise the LP is not yet available and the row data is invalid
139- SCIPcreateConsPseudobooleanWithConss(), SCIPcreateConsPseudoboolean(), and SCIPcreateConsBasicPseudoboolean(): removed `intvar` from arguments because the non-linear objective reformulation with pseudoboolean constraints did not work
140- SCIPcleanupConssLinear() and SCIPcleanupConssKnapsack(): added argument `ndelconss` to directly delete empty redundant constraints before creating problem matrix
144- SCIPpermuteProb(): argument `permuteimplvars` has been replaced by new arguments `permutebinimplvars`, `permuteintimplvars`, and `permutecontimplvars`
145- SCIPgetLPBranchCands(): implied integral variables with integrality constraints are included in `nlpcands` count and stored at the end of `lpcands`
146- SCIPgetNLPBranchCands(): implied integral variables with integrality constraints are included
147- SCIPgetSolVarsData(): argument `nimplvars` has been replaced by new arguments `nbinimplvars`, `nintimplvars`, and `ncontimplvars`
149- SCIPcreateVar() (temporarily for SCIP 10 only): attempting to create a variable with type \ref SCIP_VARTYPE_IMPLINT creates a variable of type \ref SCIP_VARTYPE_CONTINUOUS and implied integral type \ref SCIP_IMPLINTTYPE_WEAK
150- SCIPchgVarType() (temporarily for SCIP 10 only): attempting to change a variable type to \ref SCIP_VARTYPE_IMPLINT leads to a call of SCIPchgVarImplType() with type \ref SCIP_IMPLINTTYPE_WEAK
151- `SCIPapplyBendersDecomposition()` has been removed; this was originally used to apply Benders' decomposition from a supplied decomposition structure; the application of Benders' decomposition now occurs in relax_benders
152- SCIPcalcMIR(), SCIPcutGenerationHeuristicCMIR(), SCIPcalcStrongCG(): replaced boolean argument `usevbds` by an integer argument `vartypeusevbds`, which indicates for which variables variable bound substitution should be performed
153- `SCIPchgAndConsCheckFlagWhenUpgr()`, `SCIPchgAndConsRemovableFlagWhenUpgr()`: removed to keep upgrade flags consistent; use SCIPconsAddUpgradeLocks() to control upgrades instead
154- SCIPaddConflict(): argument `cons` changed to type `SCIP_CONS**` to release the conflict constraint in a clean way
155- SCIPprintOrigProblem() and SCIPprintTransProblem(): moved declaration moved from scip_solvingstats.h to scip_prob.h
156- `SCIPnlpiOracleGetJacobianSparsity()`: renamed to SCIPnlpiOracleGetJacobianRowSparsity() and added arguments `colnlflags` and `nnlnz`
170 `SCIPbendersApplyDecomposition()`, `SCIPgetExprsdataBilinear()`, `SCIPgetVarCoefChg()`, `SCIPvarGetOrigIndex()`, `SCIPallocateSymgraphConsnodeperm()`, `SCIPwriteSto()`: removed the declaration because there was no implementation
171
172### New API functions
173
174Exact Solving:
175- SCIPenableExactSolving(): enable and disable exact solving mode; see below for a list of many new API functions added to support exact solving
176- `SCIPrational*()`: create and compute with rational numbers
177- SCIPintervalSetRational(): compute interval of rational number
178- SCIPstrToRationalValue(), SCIPrationalStrLen(), SCIPrationalToString(): handle string conversion of a rational number
179- SCIPrationalChgInfinity(), SCIPrationalGetInfinity(): handle infinity threshold of rational numbers
180- `SCIPrationalarray*()`: create and handle rational arrays
181- SCIPisExact(): query whether exact solving is enabled
182- SCIPisCertified(): query whether certification is enabled
183- `SCIPcertify*()`, `SCIP*Certificate()`: support proof logging/certificate generation
184- `SCIP*MarkExact()`: mark plugins as safe to use in exact solving mode
185- `SCIP*IsExact()` : query whether objects are ready for exact solving
186- SCIPincludeConshdlrExactLinear(): include the constraint handler for exact linear constraints
187- `SCIP*ExactLinear()`: create, query, and modify an exact linear constraint
188- SCIPconsGetLhsExact()`, SCIPconsGetRhsExact(), SCIPgetConsValsExact(): query exact sides and coefficients of a linear constraint
189- `SCIPmatrix*Exact()`: query matrix information in rational arithmetic
190- SCIPaddVarExactData(): add exact data to an existing variable
191- `SCIPvarGet*Exact()`: query variable information in rational arithmetic
194- SCIPlpExactDiving(): query whether exact LP is in diving mode
195- SCIPlpExactIsSolved(): query whether the exact LP is solved
196- SCIPwriteLPexact(): write the exact LP
197- `SCIPcolExact*()`, `SCIProwExact*()`: handle the exact LP columns and rows
198- `SCIPlpiExact*()`: handle the exact LP interface
199- SCIPgetNExactLPs(): query the number of exact LP solves
200- SCIPgetLPExactSolstat(), SCIPgetLPExactObjval(): query solution status and objective value of the exact LP
201- SCIPaddOrigObjoffsetExact(), SCIPgetOrigObjoffsetExact(): add and query exact objective offset of the original problem
202- `SCIP*Sol*Exact()`: create and handle exact solutions
203- SCIPsolOrigAddObjvalExact(): add to exact objective of original solution
204- SCIPincludeConshdlrExactSol(): include the exact post-processing for solutions
205- `SCIP*Row*Exact*()`: create and handle exact LP rows
206- `SCIPaggrRow*Safely()`: compute safe real row aggregation
207- SCIPallowNegSlack(): query whether negative slacks are allowed
208- SCIPbranchLPExact(): branch exactly on the LP solution
209- SCIPeventGetOldboundExact(): query exact old bound for a bound change event
210- SCIPcalcIntegralScalarExact(): compute a scalar so that all given values become exactly integral
211- SCIPnodeGetLowerboundExact(): query the exact lower bound of a node
212- SCIPgetCutoffboundExact(), SCIPgetLowerboundExact(), SCIPgetUpperboundExact(), SCIPgetDualboundExact(), SCIPgetPrimalboundExact(): query exact best bounds on optimal value
213- SCIPvalidateSolveExact(): validate the exact solve
214
215Implicit Integrality:
216- SCIPincludePresolImplint(): include the new implied integral presolver
217- SCIPcreateVarImpl(), SCIPcreateObjVarImpl(): behave identically to SCIPcreateVar() and SCIPcreateObjVar(), respectively, but have an additional argument for the new implied integral type flag (8th position)
218- SCIPchgVarImplType(), SCIPvarGetImplType(), SCIPvarIsImpliedIntegral(), SCIPcolIsImpliedIntegral(): control and query implied integrality
219- SCIPvarIsNonimpliedIntegral(): query whether a variable is integral but not implied integral
220- SCIPgetNOrigBinImplVars(), SCIPgetNOrigIntImplVars(), SCIPgetNOrigContImplVars(): query the number of implied integral variables of each type in original problem;
221 note that SCIPgetNOrigBinVars(), SCIPgetNOrigIntVars(), and SCIPgetNOrigContVars() no longer include the implied integral variables in their counts
222- SCIPgetNBinImplVars(), SCIPgetNIntImplVars(), SCIPgetNContImplVars(): query the number of implied integral variables of each type in current problem;
223 note that SCIPgetNBinVars(), SCIPgetNIntVars(), and SCIPgetNContVars() no longer include the implied integral variables in their counts
224- SCIProwGetNumImpliedIntCols(): query number of implied integer columns in a row
225- SCIPvarsCountTypes(): determine the variable type count distribution for an array of variables
226- SCIPeventGetOldImplType(), SCIPeventGetNewImplType(): query implication type change for the new event \ref SCIP_EVENTTYPE_IMPLTYPECHANGED
227- SCIPexprGetIntegrality(): provides information about the presence of weakly implied integral variables, in addition to the existing function SCIPexprIsIntegral()
231- SCIPdisplaySymmetryGenerators(), SCIPdialogExecDisplaySymmetry(): display generators of symmetry group
232- SCIPclearSymgraph(), SCIPcopySymgraphAsSubgraph(): clear and copy a symmetry detection graph, respectively
233
234Conflict Analysis:
235- SCIPgetNResConflictConssApplied(): return the number of generalized resolution conflict constraints added to the problem
236- SCIPaddConsUpgrade(): add constraint upgrades while informing the conflict store
237
238Branching:
239- SCIPhistoryUpdateAncPseudocost(), SCIPvarUpdateAncPseudocost(): update the ancestral pseudo cost fields in variable history
240- SCIPhistoryGetAncPseudocost(), SCIPhistoryGetAncPseudocostCount(), SCIPhistoryIsAncPseudocostEmpty(), SCIPgetVarAncPseudocostVal(), SCIPvarGetAncPseudocost(): retrieve values related to ancestral pseudo cost fields in variable history
242- SCIPboundchgGetLPSolVal(): access LP solution value in the branching data of a bound change
243
244Cutting Planes:
245- SCIPincludeSepaFlower(): include the new flower cut separator
246- SCIPconsCreateRow(): to create and return the row of a linearly representable constraint
247- SCIPcreateRowKnapsack(), SCIPcreateRowLinear(), SCIPcreateRowLogicor(), SCIPcreateRowSetppc(), SCIPcreateRowVarbound(): create and get the row of linearly representable constraints
248
249Benders' Decomposition:
250- SCIPincludeRelaxBenders(): include the Benders' decomposition relaxator
251- SCIPgetMasterProblemRelaxBenders(): retrieve master problem SCIP instance from the Benders' decomposition relaxator
252- SCIPbendersGetSubproblemMasterVars(), SCIPbendersGetNSubproblemMasterVars(), SCIPbendersGetSubproblemMasterVarsData(): get the linking master variables for each subproblem and details about the number of binary and integer variables
253- SCIPsetBendersObjectiveType(), SCIPbendersGetObjectiveType(): set and get the objective type for the aggregation of the Benders' decompostion subproblems
254- SCIPbenderGetMasterAuxiliaryVar(): get master auxiliary variable
255- SCIPfreeReaderdataCor(), SCIPfreeReaderdataTim(), SCIPfreeReaderdataSto(): free the data for the COR, TIM, and STO readers, respectively; these readers are all used when reading an SMPS instance
268 SCIPhypergraphOverlapsEdgesGetAtIndex(), SCIPhypergraphVertexOverlapsFirst(), SCIPhypergraphVertexOverlapsBeyond(), SCIPhypergraphVertexOverlapsGetAtIndex(): query information about vertices, edges, and overlaps as well as their incidences
269
270Network Matrix:
271- SCIPnetmatdecCreate(), SCIPnetmatdecFree(): create and delete a network matrix decomposition
272- SCIPnetmatdecTryAddCol(), SCIPnetmatdecTryAddRow(): add columns and rows to a matrix decomposition
273- SCIPnetmatdecContainsRow(), SCIPnetmatdecContainsColumn(): check if a matrix decomposition contains the given row or columns
274- SCIPnetmatdecRemoveComponent(): remove connected components from a matrix decomposition
275- SCIPnetmatdecCreateDiGraph(): expose underlying digraph of matrix decomposition
276- SCIPnetmatdecIsMinimal(), SCIPnetmatdecVerifyCycle(): check whether certain invariants of a matrix decomposition are satisfied and used in tests
277
278Solve Statistics:
279- functions to create, modify, and free SCIP_DATATREE objects and to print as JSON or table (see pub_datatree.h and scip_datatree.h)
280- `SCIPcollect*Statistics()`: for every `SCIPprint*Statistics()` in scip_solvingstats.h
281- SCIPprintStatisticsJson(): output a JSON string of the table statistics data
282
283Nonlinearity:
284- SCIPincludeNlpSolverConopt(), SCIPsetLicenseConopt(), SCIPgetSolverNameConopt(), SCIPgetSolverDescConopt(), SCIPisConoptAvailableConopt(): interact with the new CONOPT interface
285- SCIPnlpiOracleGetConstraintLinearCoef(): get a linear coefficient of a variable in a given constraint in the NLP oracle
286- SCIPnlpiOracleGetJacobianColSparsity(): get the column-wise sparsity pattern of the Jacobian from the NLP oracle
287- SCIPnlpiOracleGetObjGradientNnz(): get indices of nonzeroes in the objective gradient
288- `src/objscip/objexprhdlr.h`: C++ interface for expression handlers
289
290Miscellaneous:
291- SCIPsortRealPtrPtr(), ..., SCIPsortDownIntIntIntReal(): new sorting functions
292- `SCIPdebugClearSol()`: clear the debug solution
293- SCIPdialogIsHidden(), SCIPdialogSetHidden(): determine whether a dialog should be hidden in help list
294- SCIPstatusName() to get a string representation of SCIP_STATUS
295- SCIPconshdlrSetNeedsCons(): set whether constraint handler callbacks should also be called if there are no constraints
296- SCIPpropSetTimingmask(): set timing mask of a propagator
298- SCIPvarGetMinAggrCoef(), SCIPvarGetMaxAggrCoef(): get bounds on absolute aggregation coefficients for a loose variable
299- SCIPisVarAggrCoefAcceptable(): check whether bounds on aggregation coefficients would exceed thresholds when using a loose variable in another aggregation
300- SCIPgetNRootIntFixings(): retrieve the number of integer fixings at the root node
301- SCIPcollectMemoryGarbage(): explicitly trigger garbage collection on block memory; before SCIP 10, this was done in SCIPtransformProb()
302
303### Data Structures
304
305- added struct \ref SCIP_RATIONAL for rational number arithmetic
306- added struct \ref SCIP_LPEXACT and many further data structures to support exact solving mode
308- added struct \ref SCIP_DATATREE to model generic serializable data; new enum \ref SCIP_DATATREE_VALUETYPE
309
310### Changes in Preprocessor Macros
311
312- `SCIP_EVENTTYPE_TYPECHANGED`: no longer generated if a variable becomes implied integral
313- `SCIP_EVENTTYPE_IMPLTYPECHANGED`: new event that is generated if a variable is declared implied integral, this event is included in the set \ref SCIP_EVENTTYPE_VARCHANGED
314- `SCIP_EVENTTYPE_DUALBOUNDIMPROVED`: new event that is generated whenever the global dual bound is improved
315- `SCIP_EVENTTYPE_GAPUPDATED`: new event mask for catching updates in primal or dual bound
316- `SCIP_PROPTIMING_NONE`: new propagator timing for never calling a propagator
317- `SCIP_HEURTIMING_NONE`: new heuristic timing for never call a primal heuristic
318- `strcasecmp`, `strncasecmp` (Windows builds): removed `#define` from scip/def.h; use SCIPstrcasecmp() and SCIPstrncasecmp() instead
325- `help <command>` now allows to display information on specific command
326- allow to hide certain commands in the help list
327- added the (hidden) command "exit" to exit the shell
328- added command `iis` to create an infeasible subsystem
329- added `write/iis` dialog to write out the infeasible subsystem to file
330- added `display/iis` dialog to write out the infeasible subsystem to console
331
332### Changed parameters
333
334- `heuristics/scheduler/heurtimelimit` removed to avoid indeterministic behavior of scheduler heuristic, uses main time limit instead
335- removed parameters `constraints/orbitope/checkpporbitope`, `constraints/orbitope/sepafullorbitope`, `constraints/orbitope/forceconscopy`, which became superfluous
336- removed `reading/gmsreader/signpower`
337- removed `benders/default/numthreads`: multi-threading support for Benders' decomposition has been temporarily disabled
338- restricted range of parameter `propagating/symmetry/sstleadervartype` to [1,7]; its new default value is 6
339- `propagating/∗/timingmask` extended by setting 0 to disable propagators completely
340- changed defaults of `constraints/components/propfreq` and `constraints/components/maxdepth` to -1 and 2147483647, respectively, to avoid unnecessary calls of components propagator by default
341- changed frequencies for the following heuristics: shifting, gins, crossover, rins, randrounding
342- changed default `maxlpiterquot` to 0.05 for all LP diving heuristics and feaspump, whereas adaptivediving uses 0.15 and rootsoldiving remains at 0.01
343- changed default of `presolving/restartminred` to 0.05
344- changed default of `presolving/immrestartfac` to 0.05
346- updated description of parameter `misc/usesymmetry`
347
348### New parameters
349
350- `exact/enable`: enable exact solving mode
351- `exact/improvingsols`: whether only improving exact solutions should be considered
352- `exact/safedbmethod`: method of safe dual bounding
353- `exact/interleavedbstrat`: interleaving strategy between safe dual bounding and exact LP solving
354- `exact/psdualcolselection`: project-and-shift strategy of dual column selection
355- `exact/cutapproxmaxboundval`: maximal absolute bound for which coefficients in exact cuts should be approximated
356- `exact/cutmaxdenom`: maximal denominator of coefficients in approximating exact cuts
357- `exact/allownegslack`: whether negative slack variables in exact Gomory cuts should be used
358- `exact/lpinfo`: whether the exact LP solver should display status messages
359- `constraints/exact{linear,sol}/{sepafreq,propfreq,proptiming,eagerfreq,maxprerounds,delaysepa,delayprop,presoltiming}`: functionality of constraint handlers exactlinear and exactsol
360- `constraints/exactlinear/sortvars`: whether binary variable coefficients should be sorted with decreasing absolute value in exactlinear constraints
361- `constraints/exactlinear/{tightenboundsfreq,propcont,limitdenom,boundmaxdenom}`: propagation of exactlinear constraints
362- `constraints/exactlinear/{maxrounds,maxroundsroot,maxsepacuts,maxsepacutsroot}`: separation of exactlinear constraints
363- `constraints/exactsol/solbufsize`: size of solution buffer in exactsol handler
364- `constraints/exactsol/{minimprove,checkfpfeasibility,checkcontimplint,abortfrac,unfixfrac}`: solution processing in exactsol handler
365- `constraints/exactsol/maxstalls`: maximal number of consecutive unsuccessful reparations in exactsol handler
367- `branching/pscost/discountfactor`, `branching/relpscost/discountfactor`: discount factor for ancestral pseudo costs in pscost and relpscost branching rules
368- `branching/collectancpscost`: enable/disable recording of ancestral pseudo costs
370 configure the dynamic max-lookahead criterion for strong branching: enable flag, fraction threshold, distribution choice, and minimum sample size
371- `constraints/cumulative/maxtime`: limit the time horizon and avoid integer overflow for unbounded variables
372- `constraints/orbitope_full/forceconscopy`, `constraints/orbitope_pp/forceconscopy`: whether non-model constraints of type full orbitope and packing/partitioning orbitope are copied to sub-SCIPs, respectively
373- `propagating/symmetry/handlesignedorbitopes`: whether to apply special symmetry handling techniques for orbitopes whose columns can be (partially) reflected
374- `propagating/symmetry/usesimplesgncomp:` whether symmetry components all of whose variables are simultaneously reflected by a symmetry shall be handled by a special inequality
375- `propagating/symmetry/dispsyminfo`: whether to print information about applied symmetry handling methods
376- `propagating/symmetry/nautymaxlevel`: limit on depth level of Nauty's search tree
377- `presolving/implint/convertintegers`: whether implied integrality should also be detected for enforced integral variables
378- `presolving/implint/columnrowratio`: ratio of rows/columns where the row-wise network matrix detection algorithm is used instead of the column-wise network matrix detection algorithm
379- `presolving/implint/numericslimit`: limit for absolute integral coefficients beyond which the corresponding rows and variables are excluded from implied integrality detection
380- `write/implintlevel`: whether integrality constraints should be written for implied integral variables (regarded by cip, mps, lp, rlp, pip, fzn, and gms writers)
381- `iis/∗`
382- `presolving/milp/enablecliquemerging`: whether to enable clique merging in PaPILO
383- `presolving/milp/maxedgesparallel`: maximal number of edges in the parallel clique merging graph
384- `presolving/milp/maxedgessequential`: maximal number of edges in the sequential clique merging graph
385- `presolving/milp/maxcliquesize`: maximal size of cliques considered for clique merging
386- `presolving/milp/maxgreedycalls`: maximal number of greedy max clique calls in a single thread
388- `relaxing/benders/continueorig`: whether original problem should continue solving after the completion of the Benders' decomposition algorithm in the Benders' relaxator, if the problem is not solved to optimality
389- `relaxing/benders/nodelimit`: node limit for the Benders' decomposition master problem in the Benders' relaxator; by default the limits from the original SCIP instance are copied
391- `lp/minsolvedepth`: lower bound on the depth at which LPs are solved
392- `reading/opbreader/maxintsize`: maximal intsize above which an OPB instance is rejected
393- `reading/nlreader/binary`, `reading/nlreader/comments`: adjust writing of `nl` files
394- `nlpi/conopt/priority`: priority of the CONOPT NLP solver
395- `randomization/randomseedshiftmultiplier`: multiplier for the shift set by ``randomization/randomseedshift`;
396 the shift is multiplied by (6*`randomseedshiftmultiplier`+1), with the default value for `randomseedshiftmultiplier` set to 10 now;
397 this default value is expected to change with every major release; setting the parameter to 0 restores SCIP 9 behavior
398
399### Other Changes
400
401- removed LP solver interface `lpi_spx1`, which used the old SoPlex interface; renamed `lpi_spx2` to `lpi_spx`
402- removed `cons_abspower.{h,c}`, `cons_quadratic.{h,c}`, and `cons_soc.{h,c}`
403
404Build system
405------------
406
407- new option `SYM=dejavu` to choose Dejavu for computing symmetries
408- changed the default for `TPI` to `tny`
409- added build flag `CHECKSTAGE=auto` to control stage checks in API function calls
410- removed `LPS` options `spx1` and `spx2`, only `LPS=spx` is available to select SoPlex now
411- removed previously deprecated `PARASCIP` option, use `THREADSAFE=false` instead to disable thread-safety
412
413### Makefile
414
415- added build flag `EXACTSOLVE=<true|false|auto>` to turn exact solving mode on, off, or turn it on if all necessary dependencies are available
416- added build flag `MPFR` (default: false) to link with the multiprecision floating-point library, needed when SoPlex is also built with `MPFR=true` for precision boosting in rational solving mode
417- added build flag `CONOPT` (default: false) to link to the CONOPT NLP solver
418- link-time-optimization can be enabled on Linux and macOS with gcc and clang by setting `LTO=true`, default is false
419- revised `SANITIZE` options: removed `SANITIZE=full`, added `SANITIZE=thread`, `SANITIZE=address`, and `SANITIZE=memory` to enable thread, address, and memory sanitizers, respectively, in addition to undefined behavior sanitizer;
420 changed default to `SANITIZE=false`
421- default settings for makefile variables in `make.project` are now only used if variable hasn't been set already
422- the symlink `$(LIBDIR)/include/papilo` should now point to the `src` subdirectory of a PaPILO repository or the headers directory of a PaPILO installation without TBB; pointing to the directory of a PaPILO repository still works, but is deprecated
423- removed option to link TBB library, as this is not used by default when PaPILO has not been built via cmake (use `USRCXXFLAGS=-DPAPILO_TBB USRLDFLAGS=-ltbb` to enable TBB for PaPILO)
424- `LPS=spx` is no longer mapped to `LPS=spx2`, which changes the name of the generated LPI libraries and binaries when using SoPlex
425- removed `OPENSOURCE` flag
426
427### Cmake
428
429- added build flag `EXACTSOLVE=<on|off|auto>` to turn exact solving mode on, off, or turn it on if all necessary dependencies are available
430- added build flag CONOPT (default: off) to link to the CONOPT NLP solver and variable `CONOPT_DIR` to specify the path to CONOPT
431- link-time-optimization can be enabled if supported by compiler by using `-DLTO=on`, default is `off`
432- replaced `SANITIZE_XYZ=(on|off)` options by `SANITIZE=(on|off|thread|address|memory)`;
433 undefined behavior sanitizer is always enabled if not `SANITIZE=off` (the default)
434- increased minimal required cmake version to 3.11
435- scip-config.cmake now defines a variable `SCIP_COMPILE_FLAGS`, which could be used to compile code that builds against SCIP via cmake;
436 currently, this only passes on the sanitizer flags that were used to build `libscip`
437- removed automatic download and build of Bliss during cmake configuration when `-DSYM=(s)bliss`;
438 a Bliss installation from https://github.com/scipopt/bliss can be specified with `-DBLISS_DIR`
439- removed option `LEGACY`
440
441Fixed bugs
442----------
443
444- fixed bug related to unreleased data for the Benders' decomposition framework; when reading an SMPS file and applying
445 Benders' decomposition, data is created that was not correctly released; also, data within the Benders' decomposition
446 framework was not appropriately reset; the data is now released/reset as expected
447- to fix a bug where duplicate cuts from different constraint handlers were not recognized, `SCIPrealHash()` was changed
448 to be stable around shortly representable numbers, and a numerical tolerance for comparing cutting plane efficacy for the aggregation
449 separator is introduced
450- accept fractional continuous implied integral variables in heuristic "completesol"
451- invalidate activity with contradicting infinity contributions
452- avoid integer overflow in cumulative constraints triggered by unbounded variables, see new parameter `constraints/cumulative/maxtime`
453- allow negative update in SCIPconsAddUpgradeLocks() to unlock constraint upgrade
454- fixed memory leaks when LP, MPS, and OPB/WBO readers abort unsuccessfully
455- removed erroneous catching of objective-changed events in intobj separator; instead, the separator no longer executes within probing with changed objective function
456- propagator dualfix no longer fixes variables to infinity to avoid issues when transferring the solution to the original problem
457- track and check bounds on the coefficients that is used for a variable in aggregations of other variables to improve numerical stability
458- corrected the upgrade of full orbitopes to packing/partitioning orbitopes in case the orbitopal symmetries form a proper subgroup of a component's symmetry group
459- aggregate integer variable to not in clique variable in cliquePresolve() of xor constraints to avoid infeasible solutions
460- fixed memory leak in dynamic partition search primal heuristic
461- fixed issue with file existence check in XML parser when SCIP was build with ZLIB support on Windows
462- fixed thread-safety issue when using CppAD and user-defined expression handler
463- fixed typo in `#pragma` directive of redistributed nauty.h
464
465Miscellaneous
466-------------
467
468- removed 4th number in SCIP version; the new format is major.minor.patch
469- changed sassy to the version included in Dejavu
470- updated ampl/mp to v4.0.3
471- the CIP reader now sets an objective offset instead of adding a variable fixed to the objective offset
472- the solchecker tool has been extended for rational values
473- SCIPclassifyConstraintTypesLinear() classify a varbound only when a binary variable is present
474- the internal limit `MAXGENNUMERATOR` has been increased to allow more generators of symmetry groups, especially for problems with many variables
475
476@page RN9 Release notes for SCIP 9
477
478@section RN924 SCIP 9.2.4
479*************************
480
481Fixed bugs
482----------
483
484- fixed bugs with counting changes in presolving of nonlinear and setppc constraints, which resulted in negative values
485- cut off dead end node to correctly track dual bound update during solving
486- no longer construct and flush the LP in SCIPwriteLP() and SCIPwriteMIP() to avoid unexpected side effects
487- apply multi-aggregations before detecting redundancy in propagation of varbound constraints to keep bound implications
488- skip bound changes when cutting off a branch-and-bound subtree
489- correct detection of doublelex matrices and their handling via orbitope constraints
490- skip attempting to free transformed problem if SCIPtransformProb() failed with an error in SCIPpresolve(), since freeing
491 the transformed problem is likely to fail as well
492- fixed memory leak in primal heuristic "scheduler" when there is a restart
493- fixed stopping when there is a candidate with a change in the LP bound for both children in strong branching of branch_fullstrong
494- fixed detection of sinks in varbound detection from cumulative constraints
495- fixed memory allocation when adding strong SBCs for enclosing orbit of symmetric subgroups (disabled by default)
496- free paths of branch-and-bound tree iteratively instead of recursively to avoid stack overflow
497- fixed rare invalid memory access when collecting symmetry information for indicator constraints
498- recompute activity bounds before checking infeasibility and redundancy in linear constraint presolving
499- skip integer variables with fractional value in reference solution when finding additional variable fixings in ALNS heuristic
500- fix call of SCIPaddExprsViolScoreNonlinear() with constant expressions (no variables)
501- fixed bug with concurrent solve w.r.t. variable indices that led to segmentation faults and fix termination test
502- adjust further bounds before checking feasibility in SCIPvarAddVlb() and SCIPvarAddVub() to detect integrality cutoff
503- fixed that the last fixed binary variable was not set after binary variables were created for linking constraints
504- fixed that when a linking constraint with only one binary variable was added during solving, it was not disabled
505- fixed set_search_limits call when using SYM=sbliss with an old patched Bliss version
506
507Build system
508------------
509
510### CMake
511
512- added workaround for recent ctest versions rejecting -R -default as arguments
513
514### Makefile
515
516- added experimental target to run cppcheck
517
518
519@section RN923 SCIP 9.2.3
520*************************
521
522Fixed bugs
523----------
524
525- avoid hashmap key error in removal of doubletons and singletons in dual presolve of setppc constraints by skipping tripleton locks
526- when upgrading to xor constraint require parity variable to be enforced integral
527- provide the depth of the applied effective root with SCIPtreeGetEffectiveRootDepth() to avert invalid globalization of constraint set changes
528- disable objective limit during lexicographic dual minimization to preserve feasibility status
529- declare infinite bound inference infeasible in SCIPinferVarLbCons() and SCIPinferVarUbCons() to maintain correct loose LP values
530- fixed update of consssorted flags in a variable expressions data when adding an additional constraint using this variable
531- corrected computation of number of variables affected by symmetry
532- fixed computation of symmetry group size
533- correct comparison conditions in checkRedundancySide() of cons_varbound.c to ensure pair redundancy
534- also for the initial LP solve force acceptance of Farkas row in SCIPlpGetDualfarkas() if all other means for obtaining a reliable Farkas proof have failed
535- avoid overwriting the cutoff flag in tightenCoefs(), preprocessConstraintPairs(), and applyFixings() of cons_varbound.c to reject infeasible solutions
536- fix memory leak in CppAD interface w.r.t. user expressions
537- adjust bound before checking feasibility in SCIPvarAddVlb() and SCIPvarAddVub() to detect integrality cutoff
538- choose incumbent solution as reference in varFixingsRins() and varFixingsDins() of ALNS heuristic to ensure integrality
539- consider variable type in selectInitialVariableRandomly() of GINS heuristic to count integral variables
540- correct fractionality sign when standardizing bounds in simplifyInequalities() of cons_linear.c
541
542Build system
543------------
544
545### CMake
546
547- disable setting the boolean variable MACOSX_RPATH to a string value to actually enable @rpath usage
548- define SOPLEX_NEEDED and ZIMPL_NEEDED to avoid syntax error in configuration file
549
550Miscellaneous
551-------------
552
553- when writing a problem with non-generic names, warnings are printed if variable or constraint names are not unique
554
555@section RN922 SCIP 9.2.2
556*************************
557
558Fixed bugs
559----------
560
561- fixed definition of slack variables of >= constraints and ranged rows in LP interface to Gurobi
562- free memory leaking singleton arrays for ignored variables in SCIPapplyHeurDualval()
563- use epsilon tolerance for bound implications of dual substitutions in dualPresolve() of cons_linear
564- fixed timeouts due to race conditions when using TPI=omp
565- fixed issues with indexing of concurrent solvers when a solver finishes (because SCIP is too fast) before others have been created when using TPI=tny
566- respect fixing if variable is declared binary in bounds section of mps file
567- fixed reading mps files with short row and column names and some fixed-form mps files with spaces in row names
568- force local bounds to adjusted value when fixing variable
569- adds missing NULL check for Benders' subproblems in feasalt cut
570- apply objective scale to pseudoboolean non-linear terms
571- impose pseudoboolean cost bound without intermediate casting
572- flatten aggregation graph before finishing presolve to accelerate evaluating an empty solution
573- respect fixed resultants in binvarGetActiveProbindex() of branch_relpscost
574- drop fixed resultants when copying pseudoboolean constraint
575- correct matrix entry when resolving aggregated variables in checkSystemGF2() of cons_xor
576- corrected symmetry detection graph of cons_and, cons_or, cons_xor, and cons_indicator
577- correct redundancy filter in consdataCreateRedundant() of cons_bounddisjunction
578- replaced unreliable comparison of node pointers by node numbers in prop_genvbounds
579- allocate memory for all integral variables in applyCliqueFixings() of heur_clique
580- fix conflict resolution for one particular case in cons_indicator
581- make interface to nauty thread safe
582- use relative epsilon tolerance to check Farkas row in SCIPlpGetDualfarkas() to avoid invalid cutoff
583- fixed bug with SOS2 constraints of size that avoided a correct enforcing
584
585Build system
586------------
587
588### Cmake
589
590- allow to set HIGHS_DIR via -D flag as well
591- reenable building and testing of SCFLP example
592- fixed that compiler flags for sanitizers were not used for compiling objects of SCIP library
593- prioritize local includes for unittests, examples, and applications to link the intended SCIP version
594- fix detection of Gurobi 11 and 12 libs on Linux
595
596### Makefile
597
598- fix use of SANITIZE=full for debug builds with GCC on Linux: removed -fsanitize=leak because it cannot be used together with -fsanitize=address
599- fix that make install SHARED=true missed to install libscipbase
600
601@section RN921 SCIP 9.2.1
602*************************
603
604Fixed bugs
605----------
606
607- apply same feasibility definition in PaPILO as in SCIP to avoid numerical inconsistencies
608- check variable cancellation in SCIPvarAddVlb() and SCIPvarAddVub() to avert wrong infeasibility
609- SCIPfreeReoptSolve() now also clears partial solutions
610- fixed bug in calculation of "fractionality score" for spatial branching candidates in cons_nonlinear
611- fixed bug with installing symmetry dialog in sub-SCIPs
612- added copy callbacks for presolvers dualagg and redvub, branching rules lookahead and cloud, primal heuristics dualval and repair, propagator nlobbt, and separators gauge and convexproj
613- respect maximal separation rounds setting by running remaining delayed separators in last round
614- replace terms consistently in applyFixings() of cons_linear to handle infinite aggregations
615
616Build system
617------------
618
619### Cmake
620
621- fix SCIP Optimization Suite build with -DSYM=(s)bliss and bliss being downloaded and built during configuration by cmake
622- fix use of a bliss cmake installation (from https://github.com/scipopt/bliss) specified via BLISS_DIR if -DSYM=(s)bliss
623
624### Makefile
625
626- the check/solchecker build can now use also GMP installations by Homebrew on macOS/arm64
627
628Miscellaneous
629-------------
630
631- the output precision for writing CIP/OPB files has been increased at several places for nonlinear constraints
632- the solchecker tool now also supports SCIP solutions without unknown or infinite values
633- generate an error if the same linear constraint is used by several indicator constraints
634
635@section RN920 SCIP 9.2.0
636*************************
637
638Features
639--------
640
641- added check for absolute and relative gap limits at end of synchronization in concurrent solving mode, in order to terminate earlier;
642 note that if the concurrent solve is stopped due to a gap limit, the "winner" solver will have an interrupted solution status and
643 its primal and dual bounds may not be the best possible ones (use SCIPgetConcurrentPrimalbound() and SCIPgetConcurrentDualbound() instead)
644- parse pseudoboolean constraint from CIP format (and add linear-"and"-reformulation)
645
646
647Performance improvements
648------------------------
649
650- reoptimization now also stores propagations from propagators if reoptimization/saveconsprop is enabled;
651 the parameter will be renamed to reoptimization/saveprop in a next major release
652- imposed stricter limits on the size of disconnected components which may be solved separately during presolve
653- use individual slack variables also for constraints indicated by a common binary variable to use tighter formulation by default
654- when computing symmetries using Nauty, iteration limits are now available to terminate Nauty early
655
656Fixed bugs
657----------
658
659- Benders' decomposition subproblems that are always infeasible are correctly handled and the complete problem is declared infeasible
660- skip linear constraint propagation if the residual activity bound cancels the side precision
661- correct bound tracking to make the evaluation of primal-dual-integrals work
662- skip aggregations on fixed variables in milp presolver to avoid errors for earlier versions of PaPILO
663- use indices of negation counterparts and accept fixings when ordering and-resultants of pseudoboolean constraints
664- update locks on model variables before removing pseudoboolean constraints in presolve
665- reformulate soft pseudoboolean constraints with linear constraints if the indicator decomposition is disabled
666- add workaround for recent HiGHS versions resetting the model status when changing the presolve option after a solve
667- avoid hashmap key error in removal of doubletons and singletons in dual presolve of setppc constraints by updating constraints and corresponding hashmaps after each multi-aggregation
668
669Interface changes
670-----------------
671
672### New API functions
673
674- added SCIPtpiIsAvailable() to check whether a working task processing interface is available (TPI != none)
675- added SCIPtpiGetLibraryName() and SCIPtpiGetLibraryDesc()
676- SCIPdelCons() can now also be called in SCIP_STAGE_TRANSFORMED
677- added SCIPstrcasecmp() and SCIPstrncasecmp() for case-insensitive string comparison
678- added SCIPbendersSubproblemsAreInfeasible() to return if at least one subproblem has been identified as being
679 infeasible prior to performing any variable fixing
680
681### New parameters
682
683- presolving/milp/abortfacexhaustive to control the abort threshold for exhaustive presolving in PAPILO
684- presolving/milp/abortfacmedium to control the abort threshold for medium presolving in PAPILO
685- presolving/milp/abortfacfast to control the abort threshold for fast presolving in PAPILO
686- constraints/components/maxcompweight to determine the maximum weight for a disconnected component that is solved during presolve
687- constraints/components/contfactor counts the contributing factor of a single continuous variables with respect to the weight limit specified by constraints/components/maxcompweight
688- constraints/indicator/usesameslackvar to decide whether the same slack variable should be used for indicators constraints with common binary variable
689- propagating/symmetry/nautymaxncells and propagating/symmetry/nautymaxnnodes to set iteration limits in Nauty (only available if build with SYM=nauty or SYM=snauty)
690
691### Changed parameters
692
693- presolving/milp/threads is now only available if PaPILO is built with TBB
694- changed default of numerics/recomputefac to 1e+6 to aim at relative epsilon precision
695
696Build system
697------------
698
699### Cmake
700
701- attempted to fix detection of CPLEX library on macOS and Windows systems
702
703Testing
704-------
705
706- added parameter FILTER for tests/Makefile to run only tests with a specific pattern (ctest with -R FILTER)
707
708Miscellaneous
709-------------
710
711- adjusted Gurobi interface for Gurobi 12
712- reordered events: BESTSOLFOUND/NODE_FEASIBLE are now processed before the nodes are cut off and before NODE_DELETE events are processed
713- removed `#define` of `getcwd` (in case of Windows builds) in scip/def.h
714- the `#define` of `strcasecmp` and `strncasecmp` (in case of Windows builds) in scip/def.h will be removed with SCIP 10;
715 use `SCIPstr(n)casecmp()` (scip/pub_misc.h) instead
716
717@section RN911 SCIP 9.1.1
718*************************
719
720Fixed bugs
721----------
722
723- fix bug in separator aggregation that caused incorrect terminations when for an integral objective the objective limit was set to a fractional value
724- fix bug in memory management of doublelex matrices where indices were set beyond array bounds
725- store relevance flags in consdataTightenCoefs() of cons_linear.c to avoid dropping variables unintentionally due to numerical changes
726- fix possible segmentation fault when resetting local and global bounds of original variables after abnormal termination
727- compare coefficient scales to detect parallelism to avoid integral relaxations in detectRedundantConstraints() of cons_linear.c
728- remove coefficient information from linear constraint hashes in order to compare keys with tolerances
729- fixed NULL pointer dereference in SCIPtpiGetNumThreads() of TinyCThread interface if called before SCIPtpiInit(); now returns 0 in this case
730- calling SCIPsolveConcurrent() when SCIP was compiled without a TPI now results in a plugin-not-found error
731- fixed LPI status functions of lpi_cpx if the barrier is called
732- check cuts for redundancy after scaling in cutTightenCoefs() and cutTightenCoefsQuad() of cuts.c
733- maintain definition of artificial integral variables in xor constraints to avoid invalidation of conflict constraints
734- free childless nodes only after the deactivation of the old focus path in treeSwitchPath() of tree.c
735- only normalize rows for column norm evaluations in shift-and-propagate heuristic to avoid unscaled violations
736- expression handler for absolute value computes now also a cut when one of the bounds is infinite as long as the sign of the argument is known
737- check for more data to be freed before modifying nonlinear constraints in SCIPaddExprNonlinear()
738- allow for terms with zero coefficients when checking sum in SCIPexprCheckQuadratic()
739- do not abort writing of constraints to lp/pip files (and forget to free buffer memory) when encountering unsupported nonlinear constraint
740- fixed that strings with names and descriptions of the LPI's were not null-terminated
741- fixed decision on when to enforce nonlinear constraints on relaxation solutions if integer variables are present
742- fixed reading of very long lines (>78000 characters) in FlatZinc reader
743- fixed write of strings with at least 1024 characters when compiling with MSVS 2015 (14.0) or later (still an issue with earlier MSVS, which will not be fixed)
744- keep epsilon coefficients in applyFixings() of cons_linear.c until multiples are merged to avoid loss of relevant contributions
745- fixed that some variable type changes were not accounted correctly in presolve of linear constraints
746- fix constraint sorting in setpp-orbitope upgrade in symmetry code
747- fixed that SCIPnodeGetConsProps() also counted bound changes from propagators
748- use original and-constraints of an untransformed pseudoboolean constraint when copying original problems to avert segmentation faults
749- sort and-constraints of a pseudoboolean constraint with respect to the resultant problem indices to avoid shuffled copies
750- treat pseudoboolean constraints as nonlinear constraints in OPB reader to prevent duplication mistakes
751
752Examples and applications
753-------------------------
754
755- in example Binpacking implement Farkas pricing for packings because branching can actually lead to infeasible restricted master LPs
756
757Testing
758-------
759
760- allow unknown parameters to let tests pass if only optional dependencies are missing
761
762Build system
763------------
764
765### Cmake
766
767- fixed compilation and linking with HiGHS; to use HiGHS, cmake now requires to specify the directory containing the `highs-config.cmake` file via `-DHIGHS_DIR`
768- extended identification of Ipopt library on Windows to also look for ipopt.dll.lib, as this is used since Ipopt 3.13.0 (2019)
769
770
771@section RN910 SCIP 9.1.0
772*************************
773
774Features
775--------
776
777- added constraint handler that checks and enforces bounds on original variables which have been fixed or aggregated in the transformed problem
778- allow for implicit integer variables in xor constraints
779- implemented symmetry detection callbacks for pseudoboolean constraints
780- added option to consider enforcement of nonlinear constraints (including spatial branching) before integrality has been enforced
781
782Fixed bugs
783----------
784
785- make sure that, in dual proof analysis, upgraded constraints can report their number of variables
786- check knapsack constraints as linear constraints to avoid violations based on implicit integrality
787- make sure that symmetry detection callbacks report success
788- make arithmetics in cuts.c more robust to avoid invalid scg cuts due to numerical rounding sensitivity
789- allow to copy pseudoboolean constraints even if no AND constraints are present in order to avoid a warning
790- set value for variable that is introduced to reformulate nonlinear objective function when reading .nl files with initial solution
791- fixed that multi-aggregations from PaPILO were accepted without ensuring that their bounds hold
792
793Examples and applications
794-------------------------
795
796- TSP: removed `gzstream.h/hpp` and parse gzipped files differently
797
798Interface changes
799-----------------
800
801### New callbacks
802
803- SCIP_DECL_NLHDLRENFO takes additional parameter branchcandonly to indicate whether only branching candidates should be registered,
804 without looking for cuts or boundchanges
805
806### New API functions
807
808- new function SCIPgetExprActivityNonlinear() to get activity of nonlinear constraint
809- new function SCIPincludeConshdlrFixedvar() to include new constraint handler that checks bounds on fixed original variables
810
811### New parameters
812
813- limits/primal to terminate the solve as soon as the primal bound is at least as good as this value, same as limits/objectivestop (deprecated)
814- limits/dual to terminate the solve as soon as the dual bound is at least as good as this value
815- presolving/milp/internalmaxrounds to control the maximal rounds for each call of the milp presolver (PaPILO)
816- constraints/fixedvar/∗ to control the new constraint handler that checks bounds on fixed original variables
817- constraints/nonlinear/branching/mixfractional to specify minimal average pseudo cost count for discrete variables
818 at which to start considering spatial branching before branching on fractional integer variables
819 (default infinity means that integrality is always enforced before nonlinear constraints)
820- constraints/nonlinear/branching/fracweight to specify weight of fractionality of integer variables in spatial branching
821
822### New data structures
823
824- enum SCIP_Status has been extended by SCIP_STATUS_PRIMALLIMIT and SCIP_STATUS_DUALLIMIT to indicate termination at limits/primal and limits/dual respectively
825
826Build system
827------------
828- changed the default symmetry computation package from sassy+bliss to sassy+nauty
829- bliss source is no longer included in the source tree, but can be linked as external library (https://github.com/ds4dm/Bliss)
830- cmake now automatically downloads and installs the latest release version of SoPlex from GitHub if it is not found directly
831
832Miscellaneous
833-------------
834
835- updated nauty to version 2.8.8
836
837
838@section RN901 SCIP 9.0.1
839*************************
840
841Fixed bugs
842----------
843
844- fixed bug in detection of double lex matrices due to wrong memory allocation
845- fixed bug where parameter `limits/objectivestop` was copied to subscips in plugins which have different objectives
846- in count mode respect empty solution when problem is solved in presolving
847- fixed that SCIP may have tried to pass a negative random seed to an LP solver
848- fixed bug where conflict analysis in strong branching tried to analyze an unsuccessful LP solve
849- enable parameter limits/restarts by allowing to reach the restart limit in restartAllowed()
850- handle normalizing linear constraints in presolving with more caution to avoid numerical difficulties for integer variables with large coefficients
851- use quad precision to calculate residual activity bounds to reduce numerical errors for large variable bounds in cons_linear.c
852- in SCIPsolveProbingLP() when objective has been changed do not return cutoff due to exceeding the cutoff bound
853- set probing LP to be a relaxation only when objective has not been changed
854- declare contradicting infinities in getMinActivity() and getMaxActivity() as non-tight
855- reject farkas solution with large values to bound magnification of errors in SCIPgetFarkasProof()
856- if all variables are fixed, apply relative feasibility tolerance to avoid invalid infeasibility in applyFixings() of cons_linear.c
857- delete empty redundant knapsack and linear constraints after cleanup in SCIPmatrixCreate()
858- cleanup first constraints in SCIPcleanupConssVarbound(), SCIPcleanupConssSetppc(), and SCIPcleanupConssLogicor()
859- symmetry handling methods have not been added immediately after computing symmetries, which has been fixed
860- delay checking node limits after presolving to correctly continue up to the exceeding main node
861- simplified the objective sense assumption for the subproblems in the Lagromory separator
862- update effective root depth iteratively to avoid trapping it at a single child node
863- fixed that dualsparsify presolver did not always check do-not-multiaggregate variable flag
864- fixed bug in computing elements of orbits in orbital reduction
865
866Miscellaneous
867-------------
868
869- redefine isrelax to istight in cons_linear.c
870
871Build system
872------------
873
874### Cmake
875
876- A file cmake.log containing the changed options is written to the cmake build directory.
877- removed replacement of the settings of RelWithDebInfo
878- add compile option -ffp-contract=off or /fp:precise to enhance reproducibility across different systems
879
880### Makefile
881
882- add flags -ffp-contract=off and /fp:precise to enhance reproducibility across different systems
883
884Interface changes
885-----------------
886
887### New parameters
888
889- added parameter "propagating/symmetry/symtiming" to determine when symmetries are computed and handled
890
891### Changed parameters
892
893- Disabled "propagating/symmetry/addconsstiming" since it is not used anymore.
894- Disabled "propagating/symmetry/ofsymcomptiming" since it is not used anymore.
895
896@section RN900 SCIP 9.0.0
897*************************
898
899Features
900--------
901
902- added simplification of abs(x)^n to x^n when n is even (simplify rule POW12)
903- in expression simplification, added possibility to expand power of sum with exponents larger than 2 (simplify rule POW7)
904- in expression simplification, added possibility to expand products with sums as factor when there are more than two factors (simplify rule SP12b)
905- in expression simplification, added possibility to allow expanding power of products with fractional exponent (simplify rule POW5a)
906- can now build with Lapack (used for solving nonlinear problems) explicitly; if IPOPT is used, then Lapack is accessed through it;
907 an interface to Lapack is available in lapack_calls.h
908- added support for logical constraints in binary variables and basic logical operators (and, or, not, equal) to AMPL .nl reader
909- indicator constraints now use the same slack variable for the linear constraints if binary variables are used multiple times
910 for indicator constraints
911- new diving heuristic indicatordiving that focuses on indicator variables which control semicontinuous variables
912- updated statistics on NLP relaxation; information on convexity of NLP has been added
913- added new bandit method (EXP.3-IX) that is the new default of the ALNS heuristic
914- added dialog to display recognized permutation symmetries ("display symmetry")
915- The symmetry detection code has been completely restructured. Instead of completely encoding symmetry information in
916 prop_symmetry.c, there is a new callback for constraint handlers, which returns symmetry relevant information by
917 encoding a constraint as a node and edge colored graph. This way, also custom constraint handlers can provide
918 symmetry information.
919- added special presolving step for logicor and set covering/packing for constraints with two variables and one independent variable
920- increased the depth field of the tree structure from 16 to 30 bits and the max depth of the search tree from 65534 to 1073741822
921- added new cut selector plugin called cutsel_ensemble. Performs a superset of hybrid cutsel. Implements new filtering methods and scoring options.
922- added new branching rule based on Gomory mixed-integer cuts
923- added new branching score to the reliability pseudo-cost branching rule
924- added new cut selector plugin called cutsel_dynamic. Performs a superset of hybrid cutsel. Implements new filtering methods and scoring options.
925- added monoidal strengthening to intersection cut generation of nlhdlr_quadratic
926- extended heuristic dps to run after processing the node and to use strict limits for the reoptimization step
927- extended obbt propagator to handle variables of the linear constraints corresponding to indicator constraints
928- added new heuristic heur_scheduler that models the selection of LNS and diving heuristics as a multi-armed bandit problem
929- added nonlinear handler for signomial expressions: adds cuts based on a difference of convex functions representation
930- Delayed separators are now called if no other cuts have been found. Previously, such separators were only called near stalling or when the separation rounds limit was reached.
931- added a new separator sepa_lagromory to generate Lagromory cuts in a relax-and-cut framework, i.e., GMI cuts generated
932 at different bases that are explored in the process of solving the Lagrangian dual problem at a node. This separator
933 is OFF by default.
934- when parsing nonlinear constraints from CIP files, the * after the number in a term is now optional if followed by a variable,
935 i.e., instead of 3*<x>*<y>, now also 3<x>*<y> can be read, but 3<x><y> is not supported;
936 this allows to read some CIP files that were written with SCIP < 8
937- when running bliss, we now limit the number of actually created generators and not the ones considered by bliss
938
939Performance improvements
940------------------------
941
942- Variable conflict-based addition of Schreier-Sims cuts for symmetry handling in prop_symmetry.c does no longer use
943 an expensive explicit conflict graph construction.
944- Only run propagation of indicator constraints if relevant variables have changed.
945- Propagation of indicator constraints propagates maximal activity of linear constraint to upper bound of slack variable.
946- Added initialization of LP relaxation for SOC constraints.
947- Avoided some numerical issues when separating SOC constraints.
948- If differentation of convex expression fails in convex nlhdlr, then a perturbed point is tried.
949- Use sassy/bliss as default symmetry computation package.
950- No longer linearize indicator constraints in undercover heuristic by default.
951- Deactivate pre-root heuristic zeroobj in undercover heuristic.
952- Added new branching score tiebreaker for reliability pseudo-cost branching rule
953- Try nearest bound if zero solution value is out of bounds in heuristic trivial.
954
955Interface changes
956-----------------
957
958### New and changed callbacks
959
960- Added solution linearization callback for nonlinear handlers.
961 The nonlinear handler may use this callback to add tight cuts that use the given solution as reference point to the cutpool.
962 The callback is called if option constraints/nonlinear/linearizeheursol is enabled.
963- The callback for copying problem data SCIP_DECL_PROBCOPY() now has a parameter "original" indicating whether the original
964 or transformed problem should be copied. Similarly, SCIPprobCopy() in prob.h/c has such a parameter.
965- Added CONSGETPERMSYMGRAPH and CONSGETSIGNEDPERMSYMGRAPH callback for constraint handlers, which provides symmetry information about constraints to SCIP.
966
967### Deleted and changed API functions
968
969- SCIPtpiInitLock(), SCIPtpiDestroyLock(), SCIPtpiInitCondition(), SCIPtpiDestroyCondition() now take a double
970 pointer to SCIP_LOCK/SCIP_CONDITION, respectively.
971- Renamed SCIPtpiSumbitJob() to SCIPtpiSubmitJob().
972- SCIPcreateConsIndicatorLinCons(), SCIPcreateConsIndicatorGenericLinCons() do not allow binvar to be NULL anymore
973- Replaced SCIPnlrowSetCurvature() by SCIPsetNlRowCurvature().
974- SCIPsnprintf() now returns the required string length in case reallocation is necessary.
975- SCIPcomputeCoverUndercover() receives three more arguments which nonlinearities to cover
976- removed definition of SQRT
977- SCIPincludeObjConshdlr(), SCIPincludeConshdlr(), SCIPconshdlrCreate() receive two more arguments for the
978 conshdlr callbacks CONSGETPERMSYMGRAPH and CONSGETSIGNEDPERMSYMGRAPH
980- new parameter issigned for SCIPcomputeOrbitsSym()
981- new parameter symtype for SCIPcomputeComponentsSym()
982- new parameter symtype and permvardomaincenter for SCIPlexicographicReductionAddPermutation()
983- replaced parameters matrixdata and exprdata of SYMcomputeSymmetryGenerators() by graph
984
985### New API functions
986
987- new functions for interfacing with Lapack: SCIPlapackIsAvailable(), SCIPlapackIsAvailable(), SCIPlapackComputeEigenvalues(), and SCIPlapackSolveLinearEquations
988 These functions should be used instead of SCIPisIpoptAvailableIpopt(), SCIPcallLapackDsyevIpopt(), and
989 SCIPsolveLinearEquationsIpopt() in the context of computing eigenvalues or solving linear equations.
990 If IPOPT is available, the calls will be passed on to Ipopt's interface to Lapack.
1013- SCIPincludeCutselEnsemble(), SCIPselectCutsEnsemble() to include cutsel_ensemble or use the selection algorithm
1014- SCIPincludeBranchruleGomory() includes new gomory cut based branching rule
1015- SCIPgetVarAvgGMIScore(), SCIPincVarGMISumScore(), SCIPgetVarLastGMIScore(), SCIPsetVarLastGMIScore() set historical values used by SCIP's default branching rule
1016- SCIPincludeNlhdlrSignomial() includes the signomial nonlinear handler
1017- SCIPgetExprMonomialData() returns a monomial representation of a product expression
1018- SCIPestimateRoot() computes estimators for roots with exponent in [0,1]
1019- SCIPincludeCutselDynamic(), SCIPselectCutsDynamic() to include cutsel_dynamic or use the selection algorithm
1020- SCIPincludeSepaLagromory() to include the new Lagromory separator
1021- SCIPconsCompCheck() to compare two constraints based on their check priority
1022- SCIPgetConsPermsymGraph() and SCIPgetConsSignedPermsymGraph() to access the (signed) permutation symmetry detection graph of a constraint
1023- SCIPsetConshdlrGetPermsymGraph() and SCIPsetConshdlrGetSignedPermsymGraph() to set the (signed) permutation symmetry detection graph of a constraint
1024- SCIPconshdlrSupportsPermsymDetection() and SCIPconshdlrSupportsSignedPermsymDetection() to access whether a conshdlr supports detection of (signed) permutation symmetries
1025- new API functions for creating and manipulating a symmetry detection graph: SCIPcreateSymgraph(), SCIPfreeSymgraph(), SCIPcopySymgraph(), SCIPextendPermsymDetectionGraphLinear(),
1057 String values should not be quoted and spaces in string values are not supported.
1058- sassy can be used now as preprocessor for nauty/traces
1059- The solution status codes written to AMPL solution files now match those from https://mp.ampl.com/details.html#_CPPv4N2mp3sol6StatusE.
1060
1061### Changed parameters
1062
1063- change default value of parameter separating/filtercutpoolrel to FALSE
1064- Shrunk range of parameter "propagating/symmetry/sstleaderrule" from [0,3] to [0,2], removed "MAXCONFLICTS"-option.
1065- Removed reading/gmsreader/freeints. A default upper bound of +inf is now assumed for integer variables in GAMS (which is the case since GAMS 23.1).
1066- Disabled "propagating/symmetry/symfixnonbinaryvars" since it is not used in the new symmetry code.
1067- Replaced "propagating/symmetry/onlybinarysymmetry" with "propagating/symmetry/enforcecomputesymmetry" and set to FALSE by default.
1068- Disabled "propagating/symmetry/performpresolving" since running orbital reduction during presolving is not effective.
1069- Repurposed "propagating/symmetry/usedynamicprop" since it now also applies to lexicographic reduction.
1070- Changed default value of parameter "propagating/symmetry/addsymresacks" from FALSE to TRUE.
1071
1072### New parameters
1073
1074- separating/maxcutsgenfactor and separating/maxcutsrootgenfactor as factors (w.r.t. separating/maxcuts and
1075 separating/maxcutsroot) for limits on the number of cuts generated (which used to be constants '2')
1076- expr/pow/expandmaxexponent to specify limit on exponent when to expand power of sum
1077- expr/pow/distribfracexponent to enable expanding power of products with fractional exponents
1078- expr/product/expandalways to enable expanding any product with sums as factor (that is, also when more than two factors)
1079- nlhdlr/convex/maxperturb to specify maximal perturbation of non-differential reference points
1080- benders/default/nlpiterlimit to adjust iteration limit for NLP solver for Benders' decomposition NLP subproblems
1081- limits/objectivestop to interrupt the solve as soon as a primal solution is found
1082 that is at least as good as the given value
1083- heuristics/undercover/{coverand,coverind,covernl} to control which nonlinearities to consider (by default only "and" and nonlinear constraints)
1084- cutselection/ensemble/∗ all parameters for new ensemble cut selector
1085- cutselection/dynamic/∗ all parameters for new dynamic cut selector
1086- branching/relpscost/gmiavgeffweight specifies the weight in the relpscost branching score of the normalized efficacy of all generated GMI cuts (for a variable)
1087 branching/relpscost/gmilasteffweight specifies the weight in the elpscost branching score of the normalized efficacy of the last generated GMI cut (for a variable)
1088- nlhdlr/quadratic/usemonoidal to enable monoidal strengthening when separating quadratics with intersection cuts
1089- nlhdlr/quadratic/trackmore to collect more statistics for monoidal strengthening when separating quadratics with intersection cuts
1090- nlhdlr/quadratic/useminrep to use the minimal representation to compute cut coefficients when separating quadratics with intersection cuts
1091- nlhdlr/quadratic/sparsifycuts to enable sparsification of intersection cuts for quadratics
1092- heuristics/dps/reoptlimits to set strict limits for the reoptimization step in dps
1093- heuristics/dps/timing to run dps after processing the node
1094- heuristics/scheduler/∗ all parameters for new scheduler heuristic
1095- nlhdlr/signomial/enabled, nlhdlr/signomial/maxnundervars, nlhdlr/signomial/mincutscale: parameters for the signomial nonlinear handler
1096- separating/lagromory/freq to denote the frequency for calling Lagromory separator
1097- separating/lagromory/away to denote the minimal integrality violation of a basis variable to try separation
1098- separating/lagromory/dynamiccuts to denote whether the generated cuts be removed from LP if they are no longer tight
1099- separating/lagromory/maxroundsroot to denote the maximal number of separation rounds in the root node
1100- separating/lagromory/maxrounds to denote the maximal number of separation rounds in a non-root node
1101- separating/lagromory/nmaxcutsperlproot to denote, in the root node, the maximal number of Lagromory cuts that can be
1102 separated per explored basis of the Lagrangian dual
1103- separating/lagromory/nmaxcutsperlp to denote, in a non-root node, the maximal number of Lagromory cuts that can be
1104 separated per explored basis of the Lagrangian dual
1105- separating/lagromory/perroundnmaxlpiters to denote the maximal number of separating LP iterations that are allowed per
1106 separation round
1107- separating/lagromory/dualdegeneracyratethreshold to denote the minimum dual degeneracy rate for the separator execution
1108- separating/lagromory/varconsratiothreshold to denote the minimum variable-constraint ratio on the optimal face for the
1109 separator execution
1110- many other advanced parameters for the Lagromory separator, which are also mentioned under separating/lagromory/∗
1111
1112### Data structures
1113
1114- new data structure SYM_GRAPH to encode symmetry information from a constraint
1115- new data structure SYM_EXPRDATA to encode symmetry information from expressions
1116- replaced enum SYM_SYMTYPE by a complete new one; removed SYM_RHSSENSE, added SYM_NODETYPE and SYM_CONSOPTYPE
1117
1118Deleted files
1119-------------
1120
1121- deleted the now unused files: tpi_none.h, tpi_openmp.h, tpi_tnycthrd.h, type_tpi_none.h, type_tpi_openmp.h, type_tpi_tnycthrd.h
1122
1123Unit tests
1124----------
1125
1126- new unittests for nlhdlr_quadratic that test monoidal strengthening and the use of the minimal representation to compute cut coefficients
1127- unittests for nlhdlr_signomial
1128
1129Testing
1130-------
1131
1132- changed `set lim obj` to `set lim objective` in ctest since `obj` is no longer unambiguous
1133
1134Build system
1135------------
1136
1137### Cmake
1138
1139- New flag -DLAPACK=on for linking with Lapack (must be available in the system)
1140- added flag option "SYM=sbliss" for using sassy/bliss as a graph automorphism package
1141- use SYM=sbliss by default, since sassy and bliss are now shipped with SCIP.
1142- added flag option "SYM=snauty" for using sassy/nauty as a graph automorphism package
1143
1144### Makefile
1145
1146- added flag option "nauty" for SYM variable to specify which graph automorphism package should be used
1147- added flag option "sbliss" (sassy/bliss) for SYM variable to specify which graph automorphism package should be used
1148- added flag option "snauty" (sassy/nauty) for SYM variable to specify which graph automorphism package should be used
1149- use SYM=sbliss by default, since sassy and bliss are now shipped with SCIP
1150- New flag LAPACK for linking with Lapack (must be available in the system)
1151- A file scip/config.h is created in the build directory ($(OBJDIR)/include) now.
1152 Defining NO_CONFIG_HEADER is no longer necessary and has no effect anymore.
1153
1154Fixed bugs
1155----------
1156
1157- Number of runs in which separation is enabled will now be correct as per "separating/maxruns" parameter. Earlier,
1158 separation was enabled for "maxruns + 1" number of runs, i.e., separation was enabled even when "maxruns = 0" was set.
1159- add safeguard for number of selected cuts
1160- use double double precision for delta in activity updates of cons_linear.c
1161- sort constraints in checkSolOrig() to keep the logic of constraint handlers intact
1162- fixed make install when SHARED=no and make uninstall
1163- check absolute coefficients relative to extremal average to avoid invalid unifications in normalizeCons()
1164- enforce and check symmetry-based constraints to take their locks (in dual reductions) into account
1165- flush changes at the end of SCIPlpiSetBase() in lpi_grb.c to apply the newly set basis correctly
1166
1167Miscellaneous
1168-------------
1169
1170- The TPI has been changed to become mostly independent from the actual parallel interface during compile time.
1171 For this, the locks and conditions are now pointers to abstract structs.
1172- fixed that scip/def.h, the header for C preprocessor definition (`#define`'s), included headers for some SCIP type and function definitions
1184- fixed that scaling of rows in Gurobi interface (SCIPlpiScaleRow()) changed infinite sides to large finite ones (1e20) when scale factor is negative
1185- check whether objective limit is truly reached in SCIPlpiIsStable()
1186- if an objective limit is set and Mosek claims that it is exceeded, check that this is indeed the case in SCIPlpiIsStable()
1187- the .mps file reader was extended to additionally accept .mps files with the objective sense section on one line
1188- ensure that delayed cutpool separation does not happen if enough cuts have been found already
1189- fixed that a Gurobi or Mosek interface (LPI) could not be freed from a thread different than the one it was created in, which lead to problems when, e.g., using the concurrent optimizer
1190- in cons_varbound if both variables are fixed, instead of propagating the constraint check the feasibility of the constraint since propagating can lead to unnecessary numerical troubles
1191- fixed memory leak in branching rule "distribution"
1192- fixed that undercover did not enforce that sufficiently many variables in an and-constraints were fixed to have it linearized in the generated sub-scip
1193- fixed two bugs in cons_varbound: avoid adding variable bounds if vbdcoef is infinite and unlock/lock variables if lhs/rhs/vbdcoef are changed
1194- globalize constraint changes before bound changes during the effective root shift in treeSwitchPath() to correctly update variable locks by avoiding global bounds with outstanding bound change events when deleting constraints
1195- fixed error when attempting to copy SCIP with activated pricers
1196- remove integrality check for implicit integral variables in cons_integral.c, updated the definition for variable type implicit integer to be more explicit that these variables can take fractional values, and updated FAQ entry
1197- updated and, or, and pseudoboolean constraint handlers to better handle fractional implicit integer variables in enforcement
1198- avoid invalid strong Chvatal-Gomory cuts by ceiling with tolerance in the calculation of parameter k and flooring slack coefficients with standard epsilon tolerance as well as quad precision
1199- add missing row links to columns in SCIPflushRowExtensions() required to maintain correct row norms
1200- restrict separator intobj to solutions for which there can be no better feasible integral objective values to avoid cutting them off
1201- delay removal of clique lists from SCIPvarRemoveCliquesImplicsVbs() into cliqueCleanup() to avoid segmentation faults by incomplete cleanups after variable conversions
1202- reject sub-solutions with invalid objectives in SCIPtranslateSubSols() due to contradicting infinite contributions
1203- correct column index in getMinMaxActivityResiduals() to make presolver dualinfer work
1204- copy quiet flag from main scip's message handler to the one of solverscip in concurrent optimization
1205- avoid bound tightening cycles towards huge redundancy bounds in fullDualPresolve() to avert fatal numerical trouble in representing vertices of linear relaxations with unbounded domains
1206- fix problem where debug solution did not work if branching constraints are present
1207- update index of dominating variable on coefficient deletion in dualPresolving() of constraint handler logicor
1208- pass on flags from a redundant to the implying varbound constraint in preprocessConstraintPairs() to avoid suboptimal fixings by model relaxations
1209- apply reductions of dualinfer only if a dual solution exists (primal is bounded)
1210- before presolving is finished check solutions before retransforming them including tiny values to keep check flags consistent
1211- disable heuristics before and during presolving in benders decomposition to avoid messing up the objective structure in the solution store by dropping auxiliary variables in the required retransformations
1212- correct local flag of singleton conflict constraints in tightenSingleVar() against invalid bound globalization
1213- respect unboundedness in the computation of activity bounds in conflict.c to avoid invalid huge bounds due to small coefficients on unbounded variables
1214- ensure positive sides of a linear constraint when recognizing a set partition in rangedRowSimplify() to account for redundancy issues
1215- relax numerical conditions for variable aggregations to avert invalid variable fixings
1216- fixed harmless read of uninitialized data when creating parameters
1217- fix call of SCIPnlpiOraclePrintProblem in nlpi_worhp
1218
1219Performance improvements
1220------------------------
1221
1222- Use sassy/bliss as default symmetry computation package.
1223
1224Interface changes
1225-----------------
1226
1227### Interfaces to external software
1228
1229- added interface to nauty/traces for symmetry computation
1230- added interface to sassy, a preprocessor for symmetry computation
1231- The directory src/sassy contains the source code of sassy.
1232
1233Build system
1234------------
1235
1236### Cmake
1237
1238- added flag option "SYM=sbliss" for using sassy/bliss as a graph automorphism package
1239
1240### Makefile
1241
1242- added flag option "nauty" for SYM variable to specify which graph automorphism package should be used
1243- added flag option "sbliss" for SYM variable to specify which graph automorphism package should be used
1244- use SYM=sbliss by default, since sassy and bliss are now shipped with SCIP
1245
1246Miscellaneous
1247-------------
1248
1249- the parameter change callback is no longer called at the moment a parameter is created
1250
1251@section RN804 SCIP 8.0.4
1252*************************
1253
1254Features
1255--------
1256
1257- use quad precision in cutsSubstituteMIR() for substituting slack variables into CMIR cuts
1258- use quad precision for activity computations in cons_linear.c
1259
1260### Deleted and changed API functions
1261
1262- SCIPshrinkDisjunctiveVarSet() no longer attempts to cutoff the current node if it finds the
1263 given disjunction to be infeasible; it is now in the responsibility of the caller to act accordingly
1264
1265### New API functions
1266
1267- added SCIPskipSpace
1268- added XML parser routines from src/xml/xml.h
1269
1270### Interfaces to external software
1271
1272- updated XPRESS interface to work with XPRESS 41 as well
1273- new interface to LP solver HiGHS (lpi_highs.cpp)
1274
1275### Changed parameters
1276
1277- changed integer parameter "propagating/symmetry/recomputrestart" from range {0, 1, 2} to being fixed at value 0
1278
1279Unit tests
1280----------
1281
1282- added new checks for objective, bounds and sides inside the scaling tests in lpi/change.c
1283
1284Fixed bugs
1285----------
1286
1287- relax condition of assert in lpSolve to hold only if lp/checkstability is true
1288- OPB reader: dynamically increase the size of the line buffer for reading in getMaxAndConsDim()
1289- Enabled the solution limit checks in SCIPsolveIsStopped in solve.c when in SCIP_STAGE_PRESOLVING
1290- fix quad precision comparison for the calculation of knapsackcover constraints.
1291- force copying of symmetry constraints for concurrent solve
1292- increase the precision of double multiplications in quad precision environments
1293- corrected handling of different variable types in symmetry
1294- orbitope detection: refine computation of overlap structure and fixed bug in finding orbitope generators
1295- ensure that winner is always determined in concurrent mode
1296- when a row with invalid index range is added to the global cutpool, update the indices instead of failing with an assert
1297- update of watched literals in cons_xor.c and ensure that fixed variables are counted in propacateCons()
1298- avoid some numerical issue in check for redundant variables in linear constraints (introduced with version 8.0.2)
1299- more rows are treated as being integral in cutsSubstituteMIR() for CMIR cuts
1300- fixed several relaxations of the rhs of cuts to 0 in cuts.c
1301- avoid aggregation into a single linear constraint if they should not be upgraded (needed for indicator constraints)
1302- apply effective root changes before fork is repropagated during treeSwitchPath() in tree.c
1303- avoid invalid objective value for solutions generated from an unbounded LP relaxation in case of a nonlinear objective function
1304- disable recomputing symmetries after a restart (constraint removal is not permitted)
1305- avoid cutting off optimal solutions for small feasibility tolerances in conflict analysis
1306- initialize variable in presol_dualsparsify.c
1307- fix in presolving of variable bound constraints to use absolute instead of relative difference
1308- free variable histories in reoptimization mode
1309- handle whitespaces in interactive shell history consistently
1310- check and enforce equalities on which the objective is projected in cons_linear.c
1311- ensure row feasibilities of solution shiftings in heur_oneopt.c and heur_twoopt.c
1398- new parameters to turn on more statistics: misc/showdivingstats (diving heuristics), heuristics/alns/shownbstats (ALNS), estimation/showstats (tree size estimation)
1399
1400### Data structures
1401
1402- added nrootcalls and ncutsadded to SCIP_Cutpool
1403- added fromcutpool flag to SCIP_Row and fixed 33 bit allocation
1554 Removed support for parameterized expressions.
1555- Added support for expression types sin, cos, and entropy. Added an expression type that stores a SCIP variable.
1556- Added handling of sin and cos expressions in OSiL reader.
1557- Added handling of sin, cos, and tan expressions in ZIMPL reader.
1558- Added expression handler plugin type, removed user expression type.
1559- Replaced expressions, expression trees, and expression graphs by a new implementation of expressions.
1560- Added differentiation methods (Gradients and Hessian directions) to expressions.
1561- Added integrality information to expressions.
1562- Added comparison and hashing of expressions.
1563- Improved simplification of expressions and identification of common subexpressions, in particular terms that appear
1564 equally in several quadratic functions are now identified.
1565- Expression simplification now expands powers also when the resulting exponents will be larger than 2.
1566- Added table to print statistics on expression handlers.
1567- Removed interval-arithmetic evaluation from expression interpreter (interfaces to automatic differentiation codes).
1568- Hessians for user-provided expression handlers are not available in the NLP solver interfaces for now.
1569- Sparse Hessians are now returned by expression interpreter. Removed dense Hessians.
1570
1571Constraint handlers for NLP:
1572- cons_nonlinear has been completely rewritten and now handles constraints of the form lhs <= expr <= rhs, where
1573 expr is an expression using the new expression type. A linear part of a nonlinear constraint is no longer distinguished.
1574- Methods that work on a particular nonlinear structure are now implemented via nonlinear handlers (nlhdlr).
1575 These handlers are plugins of cons_nonlinear and interact with cons_nonlinear by detecting structures in expressions and
1576 providing propagation and separation mechanisms.
1577- Added nlhdlr "default" as a mandatory nlhdlr: this is a nlhdlr that gets active on expressions that no other nlhdlr handles.
1578 It then uses the callbacks implemented in expression handlers to provide domain propagation and linear under/overestimates.
1579- Added nlhdlr for quadratic expressions: domain propagation that was previously part of cons_quadratic; separation via intersection cuts (currently disabled).
1580- Added nlhdlr for bilinear expressions: collects bilinear products and provides under/overestimation of a product over a 2D-projection of the LP.
1581- Added nlhdlr for convex and concave expressions: detection of convex/concave subexpressions and linear under/overestimation.
1582- Added nlhdlr for quotients: detects quotients, provides specialized linear under/overestimation and domain propagation for univariate quotients.
1583- Added nlhdlr for perspective reformulations: detects expressions in semi-continuous variables and tightens linear
1584 under/overestimates of these expressions by applying a perspective transformation.
1585- Added nlhdlr for second-order cones: detects second-order cone constraints (as ||x|| <= t or a quadratic that can written like that) and
1586 separates on a disaggregated reformulation (similar to cons_soc previously).
1587- Removed constraint handlers abspower, bivariate, quadratic, and soc.
1588- Removed simplification of duplicate abspower constraints for now.
1589 Removed simplification of abspower constraints with loose variables.
1590 Removed resolving of domain propagation (ConsResProp callback) and conflict analysis for abspower constraints.
1591 Removed propagation of varbounds for variables of abspower constraints.
1592 Removed reformulation of abs(x)^p * x into signpower expression for now.
1593- Removed reformulation of SOC constraints when adding to the NLP.
1594 Removed possibility to add linearizations a la Glineur or BenTal&Nemirovski for SOC constraints.
1595- Removed possibility to disaggregate quadratic constraints.
1596 Removed lifted tangent inequalities for bilinear terms in quadratic constraints.
1597 Removed option to project LP solution onto feasible region of a quadratic constraint via interior point or gauge function.
1598 Removed handling of unbounded LPs when enforcing quadratic constraints.
1599- Removed construction of cuts from interval gradients for nonlinear constraints.
1600 Removed possibility to pretend that all nonlinear constraints are convex.
1601 Removed possibility to create local or non-initial nonlinear constraints for now.
1602- Removed explicit reformulation of nonlinear constraints in presolve.
1603 An extended formulation is now generated implicitly and used to construct the LP relaxation,
1604 but the original formulation is used to check feasibility, propagate variable domains, etc.
1605 Variables that are added for the extended formulation are now marked as relaxation-only.
1606- Improved locking of nonlinear variables in nonlinear constraints by taking monotonicity into account.
1607- Improved mechanisms to detect and handle structures in nonlinear constraints, which allows for several algorithms
1608 to work simultaneously on equal or overlapping expressions.
1609- Improved linearization of (sums of) products of binary variables, e.g., clique information is now taken into account.
1610 Removed option to linearize products between a binary and a non-binary variable.
1611- Nonlinear constraints with the same function (but possibly different left- or right-hand-side) are now merged.
1612- When a variable appears in only one concave less-or-equal constraint, it will be fixed to one of its bounds in more cases now.
1613- New branching rule for variables in nonlinear constraints (implemented in cons_nonlinear) that scores candidates
1614 based on constraint violation, variable type, and pseudo-costs simultaneously.
1615- Added tables to print statistics of nonlinear constraint handler and nonlinear handlers.
1616
1617Performance improvements
1618------------------------
1619
1620- Use the objective cutoff row as base row for separation in sepa_aggregation.c.
1621- Separate lifted cover cuts based on newer lifting function of Letchford and Souli (2019) in sepa_aggregation.c.
1622- In-tree restarts due to tree size estimation have been made compatible with orbital fixing.
1623- Improved upgrade of orbisacks to packing/partitioning orbitopes.
1624- Improved running time of symresack cover separation.
1625- Improved propagation algorithm for orbisack and symresack.
1626- Improved handling for expressions of type signpower in CppAD interface by making use of CppADs conditional expressions.
1627- Faster reevaluation of Hessian for quadratic expressions in CppAD interface.
1628- Enabled optimization of taped expressions in the CppAD interface.
1629- Sparse Hessian evaluation for expressions with sparse Hessian in the CppAD interface.
1630- Disabled branching on variables that are added for the extended formulation of a nonlinear constraint.
1631- Prefer branching on variables in nonconvex terms of nonlinear constraints also if a cut could be generated but would yield a small reduction in the convexification gap only.
1632- When violations of nonlinear constraints are tiny, the feasibility tolerance for the LP relaxation may now be reduced temporarily to allow for cuts to have an effect.
1633- Improved under/overestimation of multidimensional vertex-polyhedral (e.g., multilinear or concave) functions by use of scaling and keeping the cut-generating LP around.
1634- Products in nonlinear constraints are no longer disaggregated for the extended formulation.
1635- No longer relax bounds of integral variables when computing bounds on activity in nonlinear constraints.
1636- Revised and improved Ipopt interface.
1637- Revised and improved subNLP primal heuristic, in particular choice of iteration limit and starting condition and reuse of subSCIP.
1638- Merge strongcg into the gomory separator to avoid computing the same base equality twice. The files
1639 sepa_strongcg.{h|c} have been removed.
1640- The RENS neighborhood in ALNS now fixes fractional variables if necessary for reaching its target fixing rate.
1641- Use cpsolver emphasis in sepa_rapidlearning.
1642- If decomposition/maxgraphedge = 0, the computation of the block graph is completely turned off.
1643- Fixed a performance bug in cons_integral.c where rounding information was passed incorrectly to the generic diving algorithm.
1644
1645Examples and applications
1646-------------------------
1647
1648- Add c++ Sudoku example
1649- Removed circle.c and renamed string.c to spring.c in CallableLibrary example.
1650- SCIP-Jack (Steiner tree application):
1651 Most files have been modified and many new ones have been added (code base more than doubled).
1652 Two new problem classes are supported: maximum-weight connected subgraph problem with budget constraints, partial-terminal node-weighted Steiner tree problem.
1653 Major performance improvements accross all problem classes that are supported.
1654
1655Interface changes
1656-----------------
1657
1658### New and changed callbacks
1659
1660- extend SEPAEXEC{LP,SOL} callbacks by parameter "depth", which should be used within separation instead of SCIPgetCurrentDepth()
1661- extend SCIPseparateSolCutpool() by parameter "pretendroot", which is passed to SCIPcutpoolSeparate() instead of SCIPtreeGetCurrentDepth(scip->tree) == 0
1679- added SCIP_NLPIPROBLEM* problem to SCIP_DECL_NLPIGETSOLVERPOINTER
1680
1681### Deleted and changed API functions
1682
1683- When calling SCIPdelVar() in the SCIP_STAGE_PROBLEM stage, it is now documented as the user's responsibility to ensure
1684 the variable is not present in any constraints. Otherwise, SCIPsolve() now returns SCIP_INVALIDDATA.
1685- removed SCIPselectCuts(), replaced by SCIPselectCutsHybrid() of the hybrid cut selector plugin
1686- If SCIPvarMarkRelaxationOnly() is called for a variable, then this now need to happen before the
1687 variable is added to the transformed problem (SCIPaddVar()).
1688 SCIPvarMarkRelaxationOnly() will automatically call SCIPvarMarkDeletable().
1689- SCIPcomputeOrbitsFilterSym() and SCIPcomputeComponentsSym(): Type of argument componentblocked
1690 changed from SCIP_Shortbool* to unsigned*.
1691- removed SCIPsetParam()
1692- SCIPcreateConsOrbitope() and SCIPcreateConsBasicOrbitope() have two new arguments "usedynamicprop"
1693 and "mayinteract" to encode whether a dynamic reordering of the orbitope rows shall be used in
1694 full orbitope propagation and whether the orbitope might interact with other symmetry handling
1695 methods, respectively.
1696- internal function SCIPgetPropertiesPerm() has been replaced by SCIPisInvolutionPerm()
1697- internal function SCIPgenerateOrbitopeVarsMatrix() has new arguments "storelexorder", "lexorder",
1698 "nvarsorder", "maxnvarsorder" to compute and store the lexicographic order defined by an orbitope
1699- renamed SCIPcomputeArraysIntersection() and SCIPcomputeArraysSetminus() to
1700 SCIPcomputeArraysIntersectionInt() and SCIPcomputeArraysSetminusInt(), respectively, and changed
1701 their return type from SCIP_RETCODE (which _always_ was SCIP_OKAY) to void
1702- removed SCIPincludeDialogDefault(), use SCIPincludeDialogDefaultBasic() instead and check whether you also need SCIPincludeDialogDefaultSet() and SCIPincludeDialogDefaultFix()
1703- removed exprint argument from SCIPaddNlRowGradientBenderscutOpt()
1704- added copyexprhdlrs argument to SCIPcopyPlugins() (19th position)
1705- added copycutselectors argument to SCIPcopyPlugins() (10th position)
1706- removed refpoint argument from SCIPaddSquareSecant()
1707- added argument exprdata to SYMcomputeSymmetryGenerators()
1722- renamed SCIPsetNlRowExprtree() to SCIPsetNlRowExpr() and changed type of expr(tree) argument to SCIP_EXPR*
1723- SCIPenableNLP() is no longer allowed in stages INITSOLVE and SOLVING
1724- removed SCIPaddLinearConsToNlpHeurSubNlp()
1725- SCIPhasNLPSolution() now returns true also if a infeasible solution to the NLP exists; SCIPcreateNLPSol() can now also be used when only an infeasible solution to the NLP exists
1726- renamed SCIPsolveNLP() to SCIPsolveNLPParam() and added parameter SCIP_NLPPARAM param
1727- removed SCIPsolveDiveNLP(), use SCIPsolveNLPParam() instead
1775- removed SCIPnlpiOracleGetVarDegree() and SCIPnlpiOracleGetVarDegrees(), use SCIPnlpiOracleIsVarNonlinear() and SCIPnlpiOracleGetVarCounts(), respectively, instead
1776- removed SCIPnlpiOracleGetConstraintDegree(), use SCIPnlpiOracleIsConstraintNonlinear() instead
1777- removed argument messagehdlr from SCIPnlpiOraclePrintProblem() and SCIPnlpiOraclePrintProblemGams()
1778- removed SCIPcreateNlpiProb(), use SCIPcreateNlpiProblemFromNlRows() instead
1779- renamed SCIPupdateNlpiProb() to SCIPupdateNlpiProblem() and moved into scip_nlpi.{h,c}
1780- renamed SCIPaddNlpiProbRows() to SCIPaddNlpiProblemRows() and moved into scip_nlpi.{h,c}
1782- removed SCIPgetIpoptApplicationPointerIpopt(), use SCIPgetNlpiSolverPointer() instead
1783- removed SCIPnlpStatisticsCreate(), SCIPnlpStatisticsFree(), SCIPnlpStatisticsGetNIterations(), SCIPnlpStatisticsGetTotalTime(), SCIPnlpStatisticsSetNIterations(), SCIPnlpStatisticsSetTotalTime(), the struct is public now
1784- renamed LapackDsyev() to SCIPcallLapackDsyevIpopt()
1785- renamed SCIPsolveLinearProb() to SCIPsolveLinearEquationsIpopt()
1786
1787Expression interpreter:
1788- removed functions that operated with SCIPInterval
1789- changed first argument of SCIPexprintCreate() to SCIP*
1790- added SCIP* as first argument to SCIPexprintFree()
1791- added SCIP* as first argument to SCIPexprintCompile(), changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA**
1792- added arguments SCIP*, SCIP_EXPRINT*, and SCIP_EXPR* as first arguments to SCIPexprintFreeData()
1793- renamed SCIPexprintGetExprtreeCapability() to SCIPexprintGetExprCapability();
1794 added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
1795- removed SCIPexprintNewParametrization()
1796- SCIPexprintEval(): added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
1797- removed SCIPexprintEvalInt()
1798- SCIPexprintGrad(): added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
1799- removed SCIPexprintGradInt()
1800- removed SCIPexprintHessianSparsityDense() and SCIPexprintHessianDense, use SCIPexprintHessianSparsity() and SCIPexprintHessian() instead
1801
1802Expressions:
1803- removed SCIPexpropGetName(), use SCIPexprhdlrGetName() instead
1804- removed SCIPexpropGetNChildren()
1805- removed SCIPexprGetOperator(), use SCIPexprGetHdlr() instead
1806- removed SCIPexprGetOpIndex(), SCIPexprGetOpReal(), SCIPexprGetOpData(), use SCIPexprGetData() instead
1807- removed SCIPexprGetRealPowerExponent(), SCIPexprGetIntPowerExponent(), SCIPexprGetSignPowerExponent(), use SCIPgetExponentExprPow() instead
1808- removed SCIPexprGetLinearCoefs(), SCIPexprGetLinearConstant(), use SCIPgetCoefsExprSum() and SCIPgetConstantExprSum() instead
1928- renamed SCIPgetNAllBilinearTermsQuadratic() to SCIPgetNBilinTermsNonlinear() and changed argument from SCIP* to SCIP_CONSHDLR*
1929- renamed SCIPgetAllBilinearTermsQuadratic() to SCIPgetBilinTermsNonlinear() and replaced arguments by SCIP_CONSHDLR* and changed return type to SCIP_CONSNONLINEAR_BILINTERM*
1930- removed SCIPaddBilinearIneqQuadratic(), use SCIPinsertBilinearTermImplicitNonlinear() instead
1931- renamed SCIPcreateConsQuadratic() to SCIPcreateConsQuadraticNonlinear() and removed argument stickingatnode
1932- removed SCIPincludeConshdlrSOC()
1933- replaced SCIPcreateConsBasicSOC() by SCIPcreateConsBasicSOCNonlinear()
1934- deprecated SCIPcreateConsSOC(), use SCIPcreateConsBasicSOCNonlinear() instead
1935- deprecated SCIPgetNlRowSOC(), use SCIPgetNlRowNonlinear() instead
2155- Removed parameters for strongcg separator: separating/strongcg/..., i.e.,
2156 maxrounds, maxroundsroot, maxsepacutsroot, maxsepacuts, dynamiccuts. One can control the
2157 strongcg behavior throught the parameters of sepa_gomory.
2158- renamed separating/{minortho,minorthoroot,objparalfac,intsupportfac} to cutselection/hybrid/{minortho,minorthoroot,objparalweight,intsupportweight}
2159
2160### New parameters
2161
2162- It is now possible to add orbitope constraints to handle symmetries even if not all variables
2163 in a component of the symmetry group are binary. This feature can be enabled using the
2222- new parameters "branching/inference/conflictprio" and "branching/inference/cutoffprio" that allow
2223 using the different score criteria in inference branching hierarchically
2224- new parameters "heuristics/alns/nodesquotmin", "heuristics/alns/maxcallssamesol" and "heuristics/alns/initduringroot"
2225 to control neighborhoods in ALNS
2226- new parameter "benders/default/benderscut/optimality/mir" to control whether mixed-integer rounding procedure is applied to Benders optimality cuts
2227- new parameter "misc/avoidmemout" to try to avoid running into memory limit
2343- added test projection:transitivity in prob/obbt.c
2344- added reader/nl.c
2345- added test intervalarith:sincos in scip/intervalarith.c
2346- added sepa/minor.c
2347- added sepa/rlt/cuts.c
2348- added sepa/rlt/product_detection.c
2349- added sepa/rlt/separation.c
2350- added tests test_compute_symmetry:expr{1,2,3,4} in symmetry/compute.c
2351
2352Build system
2353------------
2354
2355- the separate NLPI library has been integrated into the main SCIP library;
2356 uses of NLPILIBFILE or NLPILIBSRC in Makefiles that use make/make.project
2357 should be removed
2358
2359### Cmake
2360
2361- replace flag PARASCIP by THREADSAFE
2362- option AMPL is now ON by default
2363- add -D_XOPEN_SOURCE=600 cflag for compilation on systems other than windows
2364- add compile options directly instead of modifying CMAKE_C_FLAGS and CMAKE_CXX_FLAGS
2365
2366### Makefile
2367
2368- prefix PKG_CONFIG_PATH with Ipopt's pkgconfig dir instead of postfixing
2369- replace flag PARASCIP by THREADSAFE
2370- flag AMPL is now true by default
2371- libscip has been renamed to libscipbase and libscipsolver has been renamed to libscip
2372 in order to have the same library names for makefiles and cmake. For downward
2373 compatibility libscipsolver still exists (as a link).
2374
2375Fixed bugs
2376----------
2377
2378- fixed handling of multi-aggregation in cons_symresack and cons_orbisack
2379- SCIPgetLowerbound() now consistently returns infinity when status is infeasible
2380- improved the likelihood that a solution that satisfies the nonlinear constraints in the transformed (presolved) problem is also feasible for the original problem
2381- worked around a problem with derivatives of pow at 0 with non-integer exponents in CppAD
2382- fixed that setting of feasiblity and optimiality tolerance for NLP relaxation was overwritten with defaults when solving NLP
2383- fixed variance computation in t-value computation in hypothesis testing of reliability branching
2384- fixed potential overflow in cuts.c:evaluateLiftingFunctionKnapsack()
2385- do not transfer dual reductions to main SCIP in sepa_rapidlearning if strong dual reductions are forbidden
2386- fixed a bug in cons_setppc.c:removeDoubleAndSingletonsAndPerformDualpresolve() which led to wrong variable aggregations
2387- added missing redundancy check to coefficient tightening routine in cons_varbound that led to wrong variable locks
2388- added a check of numerics to avoid wrong reductions in cons_linear.c:simplifyInequalities()
2389- fixed a bug in cons_logicor.c regarding fixed variables that were not removed
2390- presol_milp.c handles variable fixings, suggested by PaPILO, more carefully to cover all cases that can appear
2391- fixed several reproducability bugs that led to different solving paths across multiple runs with one SCIP environment
2392- fixed check of limits/absgap, which was incorrectly applied to the scaled objective of the transformed problem
2393
2394Miscellaneous
2395-------------
2396
2397- in LP, use absolute instead of relative tolerances to check whether solutions from LP solver are primal feasible
2398- when a restart occurs, SCIP now asserts (during EXITSOLVE) that all relaxation-only variables are unlocked and
2399 only captured by the transformed problem.
2400- Avoid redundant calls to LP solver when LP is already flushed and solved
2401- In SCIPdebugMsg(), SCIPsetDebugMsg(), SCIPstatDebugMsg() strip directory from filename.
2402- Recompute activity of rows when checking LP solutions instead of trusting the value given by the LP solver
2403- The define NPARASCIP has been replaced by SCIP_THREADSAFE
2404- Parameters are not reset to their default values before activating an emphasis setting; this now allows to combine
2405 different emphasis settings.
2406- If a lazy bound is set to a value that is tighter than the current global bound, then the global bound is now tightened accordingly.
2407
2408@page RN7 Release notes for SCIP 7
2409
2410@section RN703 SCIP 7.0.3
2411*************************
2412
2413Interface changes
2414-----------------
2415
2416### New API functions
2417
2418- added function SCIPwithDebugSol() to determine whether SCIP was compiled with WITH_DEBUG_SOLUTION
2419
2420- New function SCIPcreateConsBounddisjunctionRedundant() and SCIPcreateConsBasicBounddisjunctionRedundant() that allow
2421 the input to contain redundant literals.
2422
2423### Changed API functions
2424
2425- added __attribute__((format(printf,,,))) to variadic SCIP message printing functions;
2426 this enables warnings about mismatches between format string and variadic function arguments if using GCC.
2427
2428### Interfaces to external software
2429
2430- removed MATLAB interface from interfaces/matlab
2431
2432Build system
2433------------
2434
2435- Compilation will now also work in a raw tarball of the scip git repository
2436
2437### Cmake
2438
2439- Make find_package more verbose and require packages to be found. Now enabled packages that are not found result in an error.
2440
2441Fixed bugs
2442----------
2443
2444- Fixed numerical bug by creating and checking the empty solution when problem vanishes in presolving.
2445- Fixed several bugs in reoptimization.
2446- Fixed bug in cons_bounddisjunction in which a constraint leads to a cutoff.
2447- Fixed bug in reoptimization by avoiding redundant literals for bound disjunctions.
2448- Replace wrong usage of CMAKE_BINARY_DIR by PROJECT_BINARY_DIR in CMake system
2449- Fixed lpi_glop to use absl flag instead of GFlags
2450- Fixed invalid initialization of limits/softtime parameter in cons_components
2451- Fixed MIN macro not defined in some cases.
2452- Safeguard some API functions for querying solving statistics against segmentation faults after SCIPpresolve()
2453- Fixed unfreed solution in concurrent solving
2454- Make sure that logicor constraints are enforced/separated if genlogicor is true in cons_indicator.
2455 Thus, do not change constraints/logicor/sepafreq anymore, but output warning.
2456- Fixed assert that assumed infeasibility cannot occur in presol_boundshift.
2457- Fixed sign bug during creation of conflict constraints with almost zero left-hand side.
2458- Disabled call of conflict handler for conflict sets that contain relaxation-only variables.
2459- Fixed bug in cons_symresack by initializing all constraint data in constrans
2460- Avoid allowing the upgrade of linear constraints corresponding to indicators in propagation of nodes.
2461- Fixed bug in computing lex. min/max faces in dynamic orbitope propagation.
2462- Limit vbounds propagator to one sweep through all bounds per call in order to avoid an infinite loop.
2463- Fixed mismatches between formatter strings and arguments in calls to SCIP message printing functions.
2464
2465Miscellaneous
2466-------------
2467
2468- To avoid performance variablity during reoptimization, the active constraints are now stored in the same order as in the
2469 original problem.
2470- Added workaround for bug in MSVS 2019 when compiling CppAD source.
2471- The original order of variables is now only restored after presolve if `randomization/permutevars` is set to FALSE.
2472
2473@section RN702 SCIP 7.0.2
2474*************************
2475
2476Features
2477--------
2478
2479- Extended check for valid variable and constraint names in PIP writer.
2480- Indicator constraints now write the name of the linear constraint in CIP format. This avoids a complicated
2481 name matching during parsing. The old format is still supported.
2482- The objective scale and offset are now taken into account when reading/writing problems in lp/mps/fzn/pip format.
2483 This often changes the behavior when writing transformed problems.
2484
2485Performance improvements
2486------------------------
2487
2488Examples and applications
2489-------------------------
2490
2491- Add c++ Sudoku example
2492
2493Interface changes
2494-----------------
2495
2496### Deleted and changed API functions
2497
2498- deprecated SCIPsetParam(); use SCIPsetIntParam(), SCIPsetRealParam(), etc, instead
2499
2500### New API functions
2501
2502- new function SCIPcolGetVarProbindex() for accessing the probindex of a variable corresponding to a column
2503- added new sorting functions SCIPsortPtrRealRealBoolBool()
2504
2505Fixed bugs
2506----------
2507
2508- Fixed a sign bug occuring for some cases in the computation of the directed cutoff distance
2509- Fixed overflow in inference information of cumulative constraint handler
2510- Fixed problem with propfreq == 0 in cons_linear.c
2511- Fixed aggregation heuristic in sepa_aggregation.c to not use local rows when that is requested nor modifiable rows
2512- Fixed problem with incompatibility of symmetry handling in Benders decomposition
2513- Fixed parsing of small number in CIP format of nonlinear constraint
2514- Fixed problem in upgrading full orbitopes to partitioning orbitopes
2515- Fixed treatment of negated variables in parsing orbitope constraints
2516- Fixed potential indexing error in prop_vbounds.c
2517- Fixed bug in writing fzn format
2518- Revert to old parameter value when parameter change is rejected in PARAMCHGD callback
2519- Fixed order of linker flags when building AMPL interface with cmake system.
2520- Fixed bug with ofsymcomptiming == 0: now symmetry is actually computed
2521- Improved separation for SOC constraint with multiaggregated variable on right-hand-side.
2522- Fixed bug in presol_boundshift: do not shift non-active variables
2523- Fixed bug in domain propagation for SOC constraints with negative coefficient for variable on right-hand-side.
2524- Fixed bug with multi-aggregated integer variables in cons_xor.
2525- Fixed bug with changed number of variables in storing relaxation solution in probing/diving.
2526- Fixed issues with scip statistics
2527- Fixed issue with multi-aggregated variables
2528- Fixed issue in with buffer memory in cons_cumulative
2529
2530@section RN701 SCIP 7.0.1
2531*************************
2532
2533Build system
2534------------
2535
2536### Cmake
2537
2538- Fixed cmake module for Ipopt to support Ipopt 3.13
2539- Added cmake variable BLISS_LIBRARY_DIR to pass a bliss library
2540- Added warning to require minimal GCC version 4.8
2541- Renamed FindCriterion cmake findmodule to FindCRITERION
2542
2543### Makefile
2544
2545- Updated make/make.project for macOS
2546- Add SANITZERFLAGS (only OPT=dbg) to LDFLAGS also if SHARED=true (and rename SANITZERFLAGS to SANITIZERFLAGS)
2547- Fixed GCC version check in make/make.linux.gnu.dbg
2548
2549Fixed bugs
2550----------
2551
2552- Fixed handling of constant term in quadratic objective of pip-reader
2553- Fixed incorrect value string for parameter estimation/completiontype
2554- Fixed initialization of first LP which led to wrong output about LPs not resolved correctly
2555- Fixed bug in SCIPcutpoolClear() function not clearing internal datastructures properly
2556- Fixed inability to set a value in a solution if it was within epsilon to the current value
2557- Fixed problems for linking optimized code with debug library of SCIP (and vice versa) by moving debug-only members
2558 to end of SCIP structs
2559
2560Miscellaneous
2561-------------
2562
2563- Variables that are marked as relaxation-only are no longer checked against debug solutions if
2564 they are captured by the transformed problem only.
2565
2566@section RN700 SCIP 7.0.0
2567*************************
2568
2569Features
2570--------
2571
2572- Using the parameter "propagating/symmetry/recomputerestart" one can now decide to recompute symmetries after a
2573 restart or not. Previously one could just turn off symmetry computation after a restart. If orbital fixing
2574 has found a reduction before the restart occured, symmetries have to be updated to ensure correctness.
2575 To this end, the user can decide via "propagating/symmetry/disableofrestart" whether orbital fixing is disabled or
2576 whether symmetries are recomputed.
2577
2578- extended relaxators statistics in solve statistics about information on number of cutoffs, improved bounds, etc.
2579
2580- extends SMPS file reader for the stochastic information, the sto files, to read a lower bound for the discrete
2581 scenarios. The lower bound is used when creating the auxiliary variables for Benders' decomposition.
2582
2583- extended Benders framework to solve NLPs and generate optimality and feasibility cuts from their solution
2584 when the subproblem is convex nonlinear.
2585
2586- extended Benders framework to create copies of Benders decompositions that can be used in a multithreading environment
2587
2588- additional functionality has been added to enable the transfer of Benders' decomposition cuts between different SCIP
2589 instances, e.g., when used in UG
2590
2591- LP rows (SCIP_ROW) can now store pointer to a constraint from which the row originates
2592
2593- Trust region, a new LNS heuristic, has been added to SCIP as both a standalone primal heuristic heur_trustregion.c
2594 and as a neighborhood inside of Adaptive Large Neighborhood Search (heur_alns.c). This heuristic is designed to improve the
2595 heuristic performance of the Benders' decomposition algorithm. It builds upon the successful trust region approaches
2596 applied to Benders' decomposition.
2597
2598- Modularity of symmetry handling has been increased. It is now possible to use orbitopes (i.e., polyhedral symmetry
2599 handling techniques) and orbital fixing on the same instance.
2600
2601- cut strengthening enabled within the Benders' decomposition framework. This uses a mix of the Improved Magnanti-Wong
2602 method and Kelly's method. The cut strengthening is enabled by setting the paramemter
2603 "benders/<bendersname>/cutstrengthenenabled" to TRUE. The parameters "cutstrengthenmult", "noimprovelimit" and
2604 "corepointperturb" control the behavior of the cut strengthening method. Additionally, the parameter
2605 "cutstrengthenintpoint" allows the user to specify the solution that is used to initialize the core point. The options
2606 are the first LP solution, the first integer feasible solution, a relative interior point, a solution vector of all
2607 ones and a solution vector of all zeros. Also, the core point can be reinitialized after each update to the incumbent
2608 solution.
2609
2610- added option to adjust weights of different scores in relpscost (hybrid) branching rule based on degeneracy information
2611 and skip strong branching for very high degeneracy rates
2612
2613- added new SCIP_DECOMP* object to store user decompositions. The user can specify one or several decompositions by assigning variable
2614 and/or constraint labels either through the API or by reading a file in DEC format (which is one of the formats that GCG writes).
2615 This format specifies constraint labels, variable labels are inferred from that. The decomposition is transformed after presolving.
2616- statistics regarding the number of blocks, the largest and smallest blocks, the border, and the constraint graph are printed for the original decomposition,
2617 and for each decomposition after presolving.
2618- the decomposition can be used as initial decomposition for the Benders functionality of SCIP.
2619- new subsection "How to provide a problem decomposition" in the SCIP documentation
2620
2621- GINS heuristic can make use of a user-provided decomposition labels in two ways:
2622 1. by selecting a block of variables that maximizes the potential, and randomly selecting a start variable for the neighborhood and/or
2623 2. by selecting an interval of consecutive blocks as neighborhood, until fixing rate is reached. In this case, no variable is randomly selected.
2624
2625- extend potential parameter of GINS to allow computation based on local LP solution, as well
2626
2627- new primal heuristic Adaptive Diving, which registers all publicly available dive sets from other diving heuristics.
2628 At each call, it selects one of the available dive sets based on the user's score type choice (heuristics/adaptivediving/scoretype).
2629 During the solution process, the heuristics learns online which divesets reach the best score, and executes them more frequently.
2630 The statistic output for Diving heuristics has been extended to incorporate the statistics of each dive set within Adaptive diving.
2631
2632- Added new penalty alternating direction method (PADM) primal heuristic that splits the problem into several sub-SCIPs
2633 according to a user-provided decomposition. The sub-SCIPs are solved on an alternating basis until a feasible solution of
2634 the original problem is found.
2635
2636- Symmetry handling constraints (cons_orbisack, cons_orbitope, cons_symresack) now have an additional parameter to encode
2637 whether they are model constraints, i.e., define the problem, or whether they are only present to handle symmetries.
2638
2639- The symmetry code has been completely restructured. The presolvers presol_symbreak and presol_symmetry as well as the propagator
2640 prop_orbitalfixing have been merged into the single propagator prop_symmetry to avoid storing the same information
2641 multiple times. This propagator is now responsible for adding symmetry handling constraints as well as activating orbital
2642 fixing. Moreover, the new file symmetry.c contains general functions for symmetry computations like orbit computations.
2643
2644- Variables can now be marked as "relaxation-only". This flag should be used to introduce new variables that are required
2645 to define a relaxation, but that are not part of any checked constraints. Essentially, these variables should only be used
2646 in the current SCIP solve and disregarded after a restart or in SCIP copies. Hence, these variables are not copied by SCIPcopy and
2647 SCIPgetVarCopy, they are currently not used in conflict constraints, and cuts involving them are not upgraded to linear constraints.
2648 Relaxation-only variables cannot appear in the objective function.
2649
2650- The OSiL reader now supports nonlinear expressions of type "signpower".
2651
2652- Expressions of form abs(x)^p * x in a nonlinear constraint are now sometimes recognized and handled by abspower constraints.
2653
2654- If polyhedral symmetry handling methods are used (cons_orbisack, cons_orbitope, cons_symresack), it is now possible to
2655 recompute symmetries if a restart occured.
2656
2657- upgrade some more quadratic constraints to second-order cone constraints, that is,
2658 handle linear binary variables as if squared in simple upgrade and
2659 do not require bounds for variables that have a zero entry in the computed eigenvectors in the non-simple upgrade
2660
2661- new variable event when changing the variable type
2662
2663- It is no longer necessary to provide a SCIP pointer for the subproblem in SCIPaddBendersSubproblem if custom solving
2664 methods are defined. A NULL pointer can be supplied to SCIPaddBendersSubproblem. In this case, no internal Benders'
2665 cut generation methods can be used.
2666
2667- Using the parameter "constraints/symresack/checkmonotonicity" one can now decide to upgrade to packing/partitioning
2668 symresacks even if the underlying permutation is not monotone.
2669
2670- New branching rule `vanillafullstrong`, mostly for scientific purpose, with the following features:
2671 1) no cutoff or domain reduction: only branching;
2672 2) idempotent (optional): leave SCIP, as much as possible, in the same state before / after the strong branching calls
2673 - basically, do not update any statistic;
2674 3) donotbranch (optional): do no perform branching. So that the brancher can be called as an oracle only
2675 (on which variable would you branch ? But do not branch please);
2676 4) scoreall (optional): keep scoring variables, even if infeasibility is detected;
2677 5) collectscores (optional): store the candidate scores from the last call, which can then be retrieved by calling SCIPgetVanillafullstrongData();
2678 6) integralcands (optional): consider integral candidates for branching,
2679 i.e., get candidates from SCIPgetPseudoBranchCands() instead of SCIPgetLPBranchCands().
2680
2681- If a reference value (misc/referencevalue) is given, the primal-reference and reference-dual integrals are calculated automatically and printed within the SCIP statistics.
2682
2683- Locally valid cuts / rows are now considered for dual proof analysis when `conflict/uselocalrows` is set to TRUE.
2684
2685- Linking variables in the linking constraint handler (cons_linking.{ch}) can now be integer or continuous. The coefficients of the binary variables are therefore now stored as SCIP_Real.
2686
2687- To save memory, it is now possible to remove all variables from the internal symmetry data structures that are
2688 not affected by any symmetry.
2689
2690- Allow to filter first variables from orbits and transfer pseudo cost information to variables in orbit
2691
2692- Add integration of external MILP presolve library as a SCIP presolver plugin that runs on MILP problems
2693
2694- Parallelisation can be used when applying Benders' decomposition. There are two different forms of parallelisation
2695 available. The first is applying Benders' decomposition within a parallel branch-and-bound. This is achieved through
2696 the integration with the UG framework. The second is the use of shared memory parallelisation for solving the Benders'
2697 decomposition subproblems. A priority queue has been added to help with load balancing.
2698
2699- The Benders' decomposition framework can handle MINLPs. If a convex relaxation of the MINLP exists, then this is
2700 solved to generate optimality and feasibility cuts. The extensions to the framework are:
2701 - New generic solving methods to solve convex NLP subproblems.
2702 - Modification to benderscut_opt and benderscut_feas to enable the generation of cuts from convex NLPs.
2703 - Addition of benderscut_feasalt to generate feasibility cuts from an alternative subproblem that minimises the
2704 violation of infeasible problems.
2705 - Better handling of subproblem solution results
2706
2707- Adds a feasibility phase to the Benders' decomposition subproblem solving methods. The feasibility phase adds slack
2708 variables to each of the constraints to ensure feasibility of the subproblem. A large coefficient is given to these
2709 slack variables in the objective function to penalise constraint violations. The coefficients are progressively
2710 increased until all slack variables take the value 0.0.
2711
2712- Improved convexity check for Benders' decomposition subproblems. The constraints of the subproblem are now checked for
2713 convexity in the initialisation of the Benders' decomposition algorithm. This enables the solving of convex NLPs as
2714 Benders' decomposition subproblems.
2715
2716- Benders' decomposition can be applied using decomposition supplied in the DEC format. To apply Benders' decomposition
2717 the parameters decomposition/benderslabels and decomposition/applybenders must be set to TRUE.
2718
2719- new event handler event_estim.c/h that approximates search tree completion and estimates tree size
2720 to trigger restarts; many approximations of search tree completion and estimation, including WBE, SSG, and tree profile method
2721- new display column that reports approx. search tree completion during the search, and an overview in the statistics table
2722- added resources (script, tutorial, test data) to adapt tree size estimation to user instances.
2723
2724- Orbital Fixing uses a list of variables that have been fixed globally since the computation of symmetries to filter
2725 symmetries. Previously, some plugins were disabled, which is not necessary anymore.
2726
2727- A new presolver "dualsparsify" was added. It tries to combine columns (i.e. variables) to cancel nonzero coefficients in the constraint matrix.
2728
2729- The presolver "tworowbnd" was implemented with better performance.
2730
2731- To be able to calculate better bounds for the dual variables, the presolver "dualinfer" was extended by the ability to perform convex combinations of continuous columns.
2732
2733- allow disabling of pricers during solving process
2734
2735- added emphasis setting for numerically challenging instances
2736
2737Performance improvements
2738------------------------
2739
2740- Extended cut presolving by removing variables that been fixed at their bounds
2741
2742- Improved branching point selection when branching on externals branching candidates. Instead of using exactly the
2743 LP solution, a point closer to the middle of the variables domain is chosen.
2744
2745- Matrix presolvers that do not work on incomplete matrices now skip matrix creation if unsupported constraint types are detected.
2746
2747- consLockBenders callback implemented to add down locks on the Benders' decomposition auxiliary variables and
2748 up and down locks per subproblem for all master problem variables. This allows the use of presolving and propagation
2749 with Benders' decomposition.
2750
2751- improved performance of orbital fixing in several ways:
2752 store permutations in transposed form to improve cache efficency;
2753 reverse order to speed up filtering of permutations;
2754 handle variables globally fixed to 1 in list;
2755 use event handler to catch global fixings;
2756 speed up orbit computations;
2757 change handling of restarts;
2758 use only permutations that can contribute to a variable's orbit;
2759
2760- allow rapid learning at local nodes
2761
2762- allow to recompute cut without using fractional values for sepa_cgmip
2763
2764- restrict the number of the clique table nonzeros relative to the number of problem nonzeros, which could be a performance bottleneck.
2765
2766- variable fixings of LP face heuristic are now computed earlier; subproblem creation is skipped if not enough variables are fixed.
2767
2768- Improved domcol presolver to not require a complete representation of all constraints in the matrix
2769
2770- performance improvement of adaptive large neighborhood search heuristic on merely continuous problems. The heuristic
2771 stops if presolving in the sub-SCIP fixes less than 50 % of the current target fixing rate over all variables
2772 (including continuous).
2773
2774- reduce memory usage in symmetry detection by a staggered allocation with decreasing overhead for larger instances
2775
2776- improved full orbitope propagation using a static implementation or a dynamic reordering of orbitope rows by a global rank function
2777
2778- improved detection of packing/partitioning orbitopes
2779
2780- enable an in-tree restart if after a reasonable initialization, the estimated size of the remaining tree is large.
2781
2782
2783Examples and applications
2784-------------------------
2785
2786- added functions to set and get hmin and hmax for optcumulative constraints
2787
2788Interface changes
2789-----------------
2790
2791### New and changed callbacks
2792
2793- new optional callback `SCIP_DECL_DIVESETAVAILABLE` to check preconditions for this dive set, e.g., if an incumbent solution is available,
2794 which is passed as new argument to SCIPcreateDiveset(). SCIPcreateDiveset() has another new parameter "ispublic".
2795
2796- new callback `SCIP_DECL_CONSHDLRCOPY` and `SCIP_DECL_CONSCOPY` in cons_orbisack and cons_symresack
2797
2798- new `idempotent` argument to SCIPgetVarStrongbranchInt() and SCIPgetVarStrongbranchFrac(),
2799 so that statistics are not updated during the call. Likewise, new `updatecol` and `updatestat` arguments to SCIPcolGetStrongbranch().
2800
2801- callback `SCIP_DECL_CONSHDLRENFOLP` can now also return SCIP_SOLVELP as *result, which indicates to the SCIP core that the LP relaxation
2802 should be solved again because the primal feasibility tolerance of the LP has been tightened (using SCIPsetLPFeastol())
2803
2804- extension of SCIP_PQUEUE by a new callback SCIP_DECL_PQUEUEELEMCHGPOS to catch swaps as well as functionality to delete arbitrary elements from the priority queue.
2805
2806### Deleted and changed API functions
2807
2808- LPI:
2809 + now for all lp interfaces consistent requirements on SCIP_LPPAR:
2810 LPITLIM and BARRIERCONVTOL positive or zero; FEASTOL, DUALFEASTOL, LPTILIM strictly positive
2811 + now projecting SCIP_LPPAR values on feasible values for each lp interface
2812 + add interface to Glop
2813 + fixed mapping between scaling parameter values in Gurobi LPI lpi_grb
2814- Symmetry:
2815 + removed function SCIPseparateCoversOrbisack() in cons_orbisack.h since the orbitope constraint
2816 handler has its own implementation of this routine with advanced features now
2817 + renamed SCIPgetGeneratorsSymmetry() to SCIPgetSymmetry() and removed two arguments
2818 + extended function SCIPgetSymmetry(): It is possible to access both the original and
2819 transposed permutations matrix as well as the (independent symmetry) components of a permutation group now.
2820 + arguments of functions SCIPcreateConsOrbisack(), SCIPcreateConsBasicOrbisack(), SCIPcreateConsOrbitope(),
2821 SCIPcreateConsBasicOrbitope(), SCIPcreateConsSymresack(), SCIPcreateConsBasicSymresack(), and SCIPcreateSymbreakCons() extended
2822 by "ismodelcons" to encode whether the constraints are model constraints or not
2823 + the function SCIPgetSymmetry() no longer accepts the parameter recompute, but has parameter permvarmap as new input
2827 + add function SCIPcomputeOrbitsComponentsSym() to compute orbits without filtering permutations and indices of orbits for each variable
2828- SCIPallowObjProp() and SCIPallowDualReds() are deprecated and replaced by SCIPallowWeakDualReds() and SCIPallowStrongDualReds(), respectively
2829- Benders' decomposition
2830 + changed SCIPstoreBenderscutCut() in scip_benders.c to SCIPstoreBendersCut(). Where this function used to take a
2831 SCIP_BENDERSCUT pointer, it now accepts a SCIP_BENDERS pointer.
2832 + the functions SCIPsolveBendersSubproblem() no longer accepts the parameter type. The type is not a necessary
2833 argument for the subproblem solving method.
2834 + arguments of functions SCIPbendersSolveSubproblemLP(), SCIPbendersSolveSubproblemCIP(), and SCIPbendersOnlyCheckConvexRelax() changed
2835 - removed SCIPbenderscutGetNAddedCuts() and SCIPbenderscutGetAddedCutData()
2836
2837
2838### New API functions
2839
2840- new argument "onlyifcomplete" in SCIPmatrixCreate() to skip matrix creation right after detecting unsupported constraint types
2841 and new arguments to count statistics when doing a clean-up of inactive variables in the constraints before building the matrix
2842
2843- new argument "threadsafe" in SCIPcopy(), SCIPcopyConsCompression(), SCIPcopyOrig(), SCIPcopyOrigConsCompression and
2844 SCIPcopyBenders(). This argument must only be set to TRUE if the source and target SCIP instances are to be solved in
2845 parallel. Setting this argument to TRUE has a performance cost.
2846
2847- new argument "append" in SCIPsetModifiedDefaultSettingsIpopt()
2848- functions SCIPclearRelaxSolVals(), SCIPsetRelaxSolVal(), SCIPsetRelaxSolVals(), SCIPsetRelaxSolValsSol(), and SCIPmarkRelaxSolValid()
2849 receive an additional argument "relax" to store the relaxation handler as creator of the relaxation solution.
2850
2851- LP:
2852 - SCIProwGetOriginCons() now returns a SCIP_CONS* instead of a SCIP_CONSHDLR*, use SCIProwGetOriginConshdlr() for the previous behavior
2853 - SCIPcreateRowCons() and SCIPcreateEmptyRowCons() now expect a SCIP_CONS* instead of a SCIP_CONSHDLR*,
2854 use SCIPcreateRowConshdlr() and SCIPcreateEmptyRowConshdlr(), respectively, for the previous behavior
2855 - deprecated SCIPlpfeastol() and SCIPchgLpfeastol(), use SCIPgetLPFeastol() and SCIPsetLPFeastol()
2856
2857- new parameter "divecontext" for every function that queries statistics for a diveset. The context can be used to distinguish between the dive set
2858 as single (standalone) heuristic or within Adaptive Diving.
2859- new parameters "divecontext" and "iterlim" to SCIPperformGenericDivingAlgorithm() to control in which context (single,adaptive) statistics are updated.
2860
2861- SCIPcopyVars, SCIPcopy, SCIPcopyConsCompression, and SCIPgetVarCopy do not copy variables that are marked as relaxation-only,
2862 thus it cannot be assumed anymore that each active variable from the master SCIP also has a counterpart in the copy.
2863 SCIPcopy, SCIPcopyConsCompression, and SCIPcopyConss can now return *valid=TRUE if some non-checked and non-enforced constraints were not copied, e.g.,
2864 because they involved relaxation-only variables. Thus, a copy is already regarded as valid if all checked or enforced constraints were copied successfully.
2865
2866- linking constraint handler:
2867 - changed type of vals argument from int* to SCIP_Real* in SCIPcreateConsLinking() and SCIPcreateConsBasicLinking()
2868 - SCIPgetIntvarLinking() has been renamed to SCIPgetLinkvarLinking().
2869 - changed return value of SCIPgetValsLinking() from int* to SCIP_Real*.
2870 - new function SCIPgetBinvarsDataLinking().
2871
2872- SCIPbendersCheckSubproblemOptimality() now returns a boolean indicating whether the subproblem is optimal or not.
2873 Previously this result was returned through a parameter. The change was required to facilitate the integration with
2874 the UG framework.
2875
2876- deleted SCIPcombineTwoInt(), SCIPcombineThreeInt(), SCIPcombineFourInt(); use the appropriate SCIPhashTwo(), ..., SCIPhashSeven() function instead
2877
2878- SCIPsetupBendersSubproblem takes a parameter of the enforcement type.
2879
2880- SCIPcreateNlpiProb takes a hashmap to store the map between the nlrows and the index in the nlrow array.
2881
2882### New API functions
2883
2884- SCIPallowWeakDualReds() and SCIPallowStrongDualReds() replace the deprecated SCIPallowObjProp() and SCIPallowDualReds(), respectively
2885- functions have been added to facilitate the transfer of Benders' decomposition cuts between solvers in UG. These include
2886 SCIPapplyBendersStoredCuts(), SCIPbendersGetNStoredCuts(), SCIPbendersGetStoredCutData() and
2887 SCIPbendersGetStoredCutOrigData().
2888- added SCIPisConvexAbspower()
2889- new functions SCIPsolGetType(), SCIPsolGetRelax(), SCIPsolSetRelax(), SCIPsolSetLPRelaxation(), SCIPsolSetStrongbranch(),
2890 SCIPsolSetPseudo to set or query the new type attribute of a primal solution. The type attribute gives information
2891 about the origin of the solution, ie, whether it was created by a relaxation handler,
2892 by the LP relaxation, by strong branching, by the current pseudo solution, or by a primal heuristic.
2893 The meaning of the argument 'heur' in all creation methods for primal solutions such as SCIPcreateSol() stays unchanged.
2895- new API functions SCIPsetCommonSubscipParams(), SCIPtranslateSubSol(), and SCIPtranslateSubSols() shared by several Large Neighborhood Search heuristics.
2896- new API function SCIPgetLPDualDegeneracy() to get two measures for the dual degeneracy of the current LP
2897- new API functions SCIPdivesetIsAvailable() to check preconditions of a dive set and SCIPdivesetIsPublic() to check if the dive set can be used
2898 by other primal heuristics.
2899- new API functions SCIPcomputeOrbitsSym(), SCIPcomputeOrbitsFilterSym(), SCIPgetPropertiesPerm(), SCIPdetermineBinvarAffectedSym(),
2900 SCIPdetermineNVarsAffectedSym(), SCIPcomputeComponentsSym(), and SCIPextendSubOrbitope(), SCIPgenerateOrbitopeVarsMatrix() for symmetry computations
2901- new API functions SCIPvarIsRelaxationOnly() and SCIPvarMarkRelaxationOnly() to query and set, resp., whether a variable is marked as relaxation-only
2902- new API functions SCIPconshdlrGetNUpdateConss() and SCIPconshdlrGetUpdateConss(), for expert users only
2903- new API function SCIPgetNConflictDualproofsApplied()
2904- new API functions SCIPeventGetOldtype() and SCIPeventGetNewtype() for the new event when changing the variable type
2905- new API function SCIPisConvexConsQuadratic() to check whether a quadratic constraint is convex when a given set of variables would be fixed
2906- new API functions SCIPgetLPFeastol(), SCIPsetLPFeastol(), and SCIPresetLPFeastol() to get, set, and reset (to the default), respectively, the primal
2907 feasibility tolerance for the LP relaxation
2908- new API functions SCIPcleanupConss{Linear,Varbound,Setppc,Logicor,Knapsack}() to clean up inactive variables from those types of linear constraints
2909- new API function SCIPsetBendersSubproblemComp() used to add a custom comparison method for ordering the Benders'
2910 decomposition subproblem solves. The comparison method is used to help with load balancing.
2911- new API function SCIPgetRowObjParallelism to get the objective parallelism of a row
2912- new API function SCIPcolGetAge to get the age of a column
2913- added SCIPhashThree(), SCIPhashFive(), SCIPhashSix(), and SCIPhashSeven() that complement SCIPhashTwo(), SCIPhashFour() to combine 32bit integers to
2914 a 32bit hash value
2915- new API function SCIPgenerateAndApplyBendersOptCut is used to generate a Benders' optimality cut using the dual
2916 solutions. This function can be supplied vectors for the primal and dual solution for generating an optimality cut.
2917 This avoids the need for a SCIP instance to solve the Benders' decomposition subproblem and generating cuts.
2918- new API function SCIPconsAddCoef used for adding a coefficient to a linear-type constraint.
2919- new API functions SCIPconsNonlinearGetRhs, SCIPconsNonlinearGetLhs and SCIPconsNonlinearAddLinearCoef for getting the
2920 RHS and LHS from a nonlinear-type constraint and adding a linear coefficient to the constraint.
2921- new API function SCIPbendersSolSlackVarsActive for checking whether any slack variables from the feasibility phase are
2922 active in the subproblem solution.
2923- new API functions SCIPbendersSetSubproblemType and SCIPbendersGetSubproblemType sets and gets the subproblem type.
2924 This is either:
2925 - Convex constraints with continuous variables
2926 - Convex constraints with discrete variables
2927 - Non-convex constraints with continuous variables
2928 - Non-convex constraints with discrete variables
2929- new API functions SCIPbendersSetSubproblemIsNonlinear() and SCIPbendersSubproblemIsNonlinear() for setting and
2930 identifying whether the Benders' decomposition subproblems contain nonlinear constraints. Similarly, the functions
2931 SCIPbendersSetMasterIsNonlinear() and SCIPbendersMasterIsNonlinear() sets and identifies whether the Benders'
2932 decomposition master problem contains nonlinear constraints.
2933- new API function SCIPapplyBendersDecomposition for applying Benders' decomposition given a decomposition in the DEC
2934 format
2935- new API function SCIPwasNodeLastBranchParent to query if a node has been the parent of the most recent branching in the tree
2936- new API functions SCIPtreemodelInit(), SCIPtreemodelFree(), SCIPtreemodelIsEnabled(), SCIPtreemodelSelectCandidate() related to the new
2937 treemodel way of comparing branching candidates. These functions are only currently used for reliability pscost branching, but they can be used
2938 in other parts of the code.
2939- New function SCIPcalcChildEstimateIncrease() to compute the increase in the child estimation
2940- new API functions SCIPisOrbitalfixingEnabled() and SCIPgetSymmetryNGenerators() to check whether orbital fixing is
2941 enabled and to get the number of generators of the current symmetry group, respectively
2942- new API function SCIPdelNlRow() to remove a row from the NLP
2943
2944### Event system
2945
2946- new event type SCIP_EVENTTYPE_NODEDELETE to react on nodes that are about to be deleted from the tree
2947
2948### Changed parameters
2949
2950- renamed parameter "propagating/orbitalfixing/enableafterrestart" to ".../symmetry/recomputerestart"
2951- Parameter "misc/allowdualreds" is now called "misc/allowstrongdualreds"
2952- Parameter "misc/allowobjprop" is now called "misc/allowweakdualreds"
2953- changed default values of propagation (new value: 1, old value: 5) and separation frequency (new value: -1, old value: 5) in cons_orbitope.c
2954- all primal heuristics that use sub-SCIPs are disabled within the heuristics fast emphasis setting
2955- deleted parameter heuristics/localbranching/useuct, use heuristics/useuctsubscip instead
2956- changed default value of "presolving/symbreak/detectorbitopes" (new value: TRUE, old value: FALSE)
2957- extended range of "misc/usesymmetry" (new range: [0,3], old range: [0,2])
2972- changed default value of "heuristics/coefdiving/freq" (old: 10, new: -1)
2973- changed default value of "heuristics/conflictdiving/freq" (old: -1, new: 10)
2974- changed default value of "heuristics/conflictdiving/lockweight" (old: 1.0, new: 0.75)
2975- replaced parameter "numerics/lpfeastol" by "numerics/lpfeastolfactor" to specify which factor should be applied to the SCIP feasibility
2976 tolerance to initialize the primal feasibility tolerance of the LP solver
2977- enabling aggressive presolving now activates all available presolving plugins,
2978 and decreases the presolving/restartfac parameter correctly with respect to default.
2979- changed default value of heuristics/rins/nodesquot to 0.3 (was 0.1), to compensate
2980 the removal of a hard coded factor of 3.0 in the code without affecting the default behavior
2981 of the RINS heuristic.
2982- changed default value of "constraints/quadratic/empathy4and" (old: 0, new: 2)
2983- changed default value of "propagating/redcost/useimplics" (old: TRUE, new: FALSE)
2984
2985### New parameters
2986
2987- the possibility to define the Benders' decomposition auxiliary variables as implicit integer is provided. This
2988 behavior is controlled with an additional parameter in the Benders' decomposition framework.
2989- added parameter benders/<bendersname>/cutcheck to enable the generation of Benders' decomposition cuts during solution
2990 checking.
2991- constraints/orbitope/usedynamicprop: the possibility to propagate orbitope constraints by reordering the rows based on the
2992 branching strategy is provided (only possible for non-model constraints)
2993
2994- new parameters heuristics/shiftandpropagate/minfixingratelp and heuristics/locks/minfixingratelp to stop the
2995 heuristics after propagating integer fixings if no sufficient fixing of the all variables (including continuous)
2996 could be achieved. These parameters help to avoid solving LP's that are comparable in hardness to the main root LP.
2997
2998- Added parameters branching/midpull and branching/midpullreldomtrig to control by how much to move
2999 the branching point for an external branching candidate closer to the middle of the candidates domain. The
3000 default of 0.75 and 0.5, respectively, uses a point that is 75*alpha% closer to the middle of the domain, where
3001 alpha is the relative width of the candidates domain (width of local domain divided by width of global domain),
3002 if the latter is below 0.5, and alpha=1.0 otherwise. That is, with the default settings, a branching point is
3003 chosen closer to the middle of the candidates domain if the variables local domain is still similar to its
3004 global domain, but is chosen closer to the LP solution if the local domain is much smaller than the global
3005 domain.
3006
3007- Added parameter lp/minmarkowitz to set the Markowitz stability threshold (range 0.0001 to 0.9999).
3008 High values sacrifice performance for stability.
3009
3010- Added parameters benders/<bendersname>/lnsmaxcalls and benders/<bendersname>/lnsmaxcallsroot to the Benders'
3011 decomposition core. These parameters limit the number of Benders' decomposition subproblem checks, for the full
3012 branch-and-bound tree and root node respective, when solving the auxiliary problem of LNS hueristics. These
3013 parameters only have effect if the lnscheck parameter is set to TRUE.
3014
3015- Added parameter cons/linear/maxmultaggrquot to limit the maximum coefficient dynamism of an equation on which
3016 multiaggregation is performed. This replaces a compiler define of the same name.
3017 Default value is 1000, smaller values make multiaggregations numerically more stable.
3018- new global parameter heuristics/useuctsubscip that affects all LNS heuristics using common sub-SCIP parameters
3019
3020- new parameter branching/relpscost/degeneracyaware to switch degeneracy-aware hybrid branching
3021
3022- new parameter separation/rapidlearning/checkexec to check whether rapid learning is allowed to run locally
3023- new parameters separation/rapidlearning/check{degeneracy,dualbound,leaves,nsols,obj} to enable checking the respective feature for local rapid learning
3024- new parameter separation/rapidlearning/maxcalls to limit the number of rapid learning executions
3025- new parameter separation/rapidlearning/nwaitingnodes to set the number of waiting nodes before the dual bound is checked
3026- new parameter separation/rapidlearning/mindegeneracy to set the minimal threshold of degenerate basic-variables
3027- new parameters separation/rapidlearning/minvarconsratio to set the minimal ratio of unfixed variables in relation to basis size
3028
3029- new parameters to control the Benders' decomposition two-phase method.
3030 - constraints/benderslp/depthfreq: after the maxdepth is reached, then the two-phase method will only be called at
3031 nodes at a depth divisible by depthfreq.
3032 - constraints/benderslp/stalllimit: after the maxdepth is reached, if there has been no improvement in the dual bound
3033 for stalllimit number of nodes, then the two-phase method is executed for the next fractional LP solution that is
3034 encountered.
3035 - constraints/benderslp/iterlimit: after the root node, only iterlimit fractional LP solutions are used at each node
3036 to generate Benders' decomposition cuts.
3037
3038- new parameters for symmetry handling
3039 - new parameter "propagating/symmetry/maxgenerators"
3040 - new parameter "propagating/symmetry/checksymmetries"
3041 - new parameter "propagating/symmetry/displaynorbitvars"
3042 - new parameter "propagating/symmetry/conssaddlp"
3043 - new parameter "propagating/symmetry/addsymresacks"
3044 - new parameter "propagating/symmetry/detectorbitopes"
3045 - new parameter "propagating/symmetry/addconsstiming"
3046 - new parameter "propagating/symmetry/ofsymcomptiming"
3047 - new parameter "propagating/symmetry/performpresolving"
3048 - new parameter "propagating/symmetry/recomputerestart"
3049 - new parameter "constraints/symresack/checkmonotonicity"
3050 - new parameter "propagating/symmetry/compresssymmetries"
3051 - new parameter "propagating/symmetry/compressthreshold"
3052 - new parameter "propagating/symmetry/disableofrestart"
3053 - new parameter "propagating/symmetry/symfixnonbinaryvars"
3054
3055- new parameter for enabling shared memory parallelisation for solving Benders' decomposition subproblems. The parameter
3056 benders/<bendersname>/numthreads sets the number of threads used for parallel subproblem solving.
3057
3058- new parameters to control enhancements for solving MINLPs by Benders' decomposition
3059 - benders/<bendersname>/execfeasphase: enables the feasibility phase for solving the Benders' decomposition
3060 subproblems
3061 - benders/<bendersname>/slackvarcoef: the initial coefficient of the slack variable for the feasibility phase
3062 - benders/<bendersname>/checkconsconvexity: should the constraints be checked for convexity. This can be set to FALSE
3063 if you are certain that the NLP subproblem is convex.
3064
3065- new parameter presolving/clqtablefac (default value 2.0) as limit on number of entries in clique table relative to number of problem nonzeros
3066
3067- new parameter conflict/uselocalrows (default: TRUE) to incorporate locally valid cuts / rows for dual proof analysis
3068
3069- new return code SCIP_NOTIMPLEMENTED for functions, e.g., in the LPI that have not been implemented (yet)
3070
3071- new parameter separating/cgmip/genprimalsols that allows to generate initial primal solutions from Gomory cuts
3072
3073- new parameter branching/relpscost/filtercandssym to allow filtering from orbits
3074
3075- new parameter branching/relpscost/transsympscost to transfer pseudo cost information to orbit
3076
3077- new parameters for tree size estimation and restarts:
3078 - estimation/restarts/restartpolicy (default value n)
3079 - estimation/method (default value c)
3080 - estimation/restarts/restartlimit (default value 1)
3081 - estimation/restarts/minnodes (default value 1000)
3082 - estimation/restarts/countonlyleaves (default value FALSE)
3083 - estimation/restarts/restartfactor (default value 2)
3084 - estimation/coefmonoprog (default value 0.3667)
3085 - estimation/coefmonossg (default value 0.6333)
3086 - estimation/restarts/hitcounterlim (default value 50)
3087 - estimation/reportfreq (default value -1)
3088 - estimation/regforestfilename (default value "-")
3089 - estimation/completiontype (default value a)
3090 - estimation/treeprofile/enabled (default value FALSE)
3091 - estimation/treeprofile/minnodesperdepth (default value 20)
3092 - estimation/useleafts (default value TRUE)
3093 - estimation/ssg/nmaxsubtrees (default value -1)
3094 - estimation/ssg/nminnodeslastsplit (default value 0)
3095
3096- new parameter constraints/linear/extractcliques to turn clique extraction off
3097
3098- new emphasis setting emphasis/numerics to increase numerical stability of (mostly) presolving operations such as (multi-)aggregations at the cost of performance.
3099
3100- new parameters for treemodel:
3101 - new parameter branching/treemodel/enable to enable the treemodel in reliability pscost branching and possible
3102 future parts of the code where it could be used.
3103 - new parameter branching/treemodel/highrule to specify which branching rule to use when treemodel thinks the node
3104 is high in the tree.
3105 - new parameter branching/treemodel/lowrule to specify which branching rule to use when treemodel thinks the node
3106 is low in the tree.
3107 - new parameter branching/treemodel/height to specify at which (estimated) height a node is high or low in the tree.
3108 - new parameter branching/treemodel/filterhigh to specify whether to filter dominated candidates in nodes which are
3109 high in the tree.
3110 - new parameter branching/treemodel/filterlow to specify whether to filter dominated candidates in nodes which are
3111 low in the tree.
3112 - new parameter branching/treemodel/maxfpiter to specify the maximum number of fixed-point iterations to use when
3113 computing the ratio of a variable using the fixed-point method.
3114 - new parameter branching/treemodel/maxsvtsheight to specify the maximum height to compute the SVTS score exactly
3115 before approximating it using the ratio.
3116 - new parameter branching/treemodel/fallbackinf defines the fallback strategy to use when the tree size estimates
3117 obtained by SVTS are infinite.
3118 - new parameter branching/treemodel/fallbacknoprim defines the fallback strategy to use when no primal bound is known
3119 and thus SVTS would not be able to compute a tree size (it would be infinite).
3120 - new parameter branching/treemodel/smallpscost defines the value under which pscosts are considered too small to be
3121 the deciding factor for branching, in which case it may be better not to use the treemodel.
3122
3123- new parameters for symmetry handling constraint handlers to enforce that also non-model constraint are copied:
3124 - new parameter "constraints/orbisack/forceconscopy"
3125 - new parameter "constraints/orbitope/forceconscopy"
3126 - new parameter "constraints/symresack/forceconscopy"
3127
3128
3129### Data structures
3130
3131- small changes in constants of hash functions
3132- added fast 2-universal hash functions for two to seven 32bit elements with 32bit output
3133- extended SCIPpqueueCreate() by additional callback argument SCIP_DECL_PQUEUEELEMCHGPOS to catch position changes
3134- new methods SCIPpqueueDelPos() to delete elements at a specific position in the priority queue and SCIPpqueueFind() to
3135 find a specific position. It is recommended to track position changes using the new callback SCIP_DECL_PQUEUEELEMCHGPOS.
3136 In contrast, using SCIPpqueueFind() can be slow because it needs to compare the element it searches for
3137 with each slot in the queue.
3138
3139### Build system
3140
3141- The default value for DFLAGS in the non-cmake buildsystem has changed from -MM to -MMD. This will break the
3142 generation of depend.* files if that was done by a compiler call that relied on -MM. The new preferred way
3143 to handle compilation dependencies is to additionally use $(DFLAGS) when compiling the object files (.o) and
3144 to include the generated .d files in the Makefile, see also "Build system / Makefile" below.
3145
3146Unit tests
3147----------
3148 - new unit test for treemodel.
3149
3150Testing
3151-------
3152
3153 - fixed an issue that may have lead to wrong status reports in the evaluation scripts
3154
3155Build system
3156------------
3157
3158### Cmake
3159
3160- avoid problem with doubly defined object together with CPLEX
3161
3162### Makefile
3163
3164- Removed static object compilation dependency files (depend.*). If using a GCC compatible compiler, then dependency
3165 files are now dynamically created and updated during build. The new dependency files (*.d) reside next to each object
3166 file (.o) in the corresponding obj subdirectory.
3167- added support for building against Ipopt >= 3.13
3168- unify compiler switches for Intel compiler and avoid problem with doubly defined object together with CPLEX
3169
3170Fixed bugs
3171----------
3172
3173- fix and improve memory handling in symmetry computation
3174- fix shown number of applied conflicts in solving statistics
3175- fix wrongly skipping strong branching call and using old information if LP was solved with 0 iterations
3176- fix minor bug in cut score calculation
3177- fixed several bugs related to rounding locks of variables not being updated correctly
3178- small fix in cons_varbound.c to skip changing bounds of multi-aggregated variables in separation callback
3179- fixed issue in SCIPtightenVar* and SCIPinferVar* that occurs for small bound changes
3180- fixed rejecting minimal boundchange that changed sign of variable, even though SCIPisLb/UbBetter approved it
3181- fixed issue in generateCutNonConvex() which is triggered when adding quadratic constraints during the solving process
3182- fixed bug in freeing the reoptimization data if no problem exists
3183- fixed bug in SCIPreoptReleaseData() when freeing all stored constraints
3184- fixed bug when freeing the transformed problem via interactive shell if reoptimization is enabled
3185- fixed two issues related to (near-)redundant logicor constraints in presolving
3186- fixed counting of aggregations in XOR constraint handler
3187- fixed handling of unbounded solutions
3188- fixed update of LP size information when an LP error occured during probing
3189- handle special case of variable bound constraints during aggregating variables
3190- tighten sides of linear constraints before trying to upgrade them to more specialized constraints (knapsack, logic-or etc.) when calling SCIPupgradeConsLinear()
3191- fixed an issue in repair heuristic in the case of loose (noncolumn) variables
3192- allow user to correctly set heuristics/alns/(un)fixtol
3193- fixed an issue in heur_completesol which is triggered during bound widening of unbounded continuous variables
3194- fixed bug in cons_indicator if addopposite is true
3195- fixed bug in sepa_disjunctive: treat case that conflictgraph is empty
3196- added safety check in conversion to rational number to avoid overflow
3197- fixed bug in interval evaluation with power-operator in certain situations
3198- fixed behavior of SCIPmatrixCreate() regarding memory management and column generation
3199- SCIPmatrixCreate() returns complete=FALSE when locks do not add up
3200- fixed bug in sepa_oddcylce when variables are fixed
3201- fixed numerical issues related to tighter constraint sides in varbound constraint handler
3202- fixed update of watchedvars in logicor constraint handler in case of a restart during the tree
3203- fixed treatment of multi-aggregated variables in logicor constraint handler
3204- handle special case of redundant implications
3205- fixed numerical issue related to almost-0-values in pseudosolution conflict analysis
3206- fixed numerical issue related to very large greatest common dividers in linear constraint handler
3207- avoid using implications on multiaggregated variables when propagating implications
3208- fixed creation of (Lagrangian) variable bounds in the OBBT propagator
3209- fixed sorting of primal solutions
3210- fixed cleaning of clean buffer in conflict analysis
3211- avoid probing on variables with huge bounds in shift and propagate heuristic
3212- fix issue in printing solutions for variables that have been added by the dual sparsify presolver
3213- fix issue related to fixing redundant logic-or constraints after presolving
3214- fixed bug when parsing logic-or and and-constraints
3215- fixed wrong assert in updateLazyBounds()
3216- fixed bug in pricestore, which resulted in too many problem variables being added
3217- fixed bug in cons_knapsack where weight of clique was not reset after an infeasibility was detected
3218- fixed bug in presol_inttobinary which did not take into account that the aggregation could be rejected due to numerics
3219- fixed bug in debug solution mechanism in connection to variables created by presol_inttobinary
3220- fixed wrong indexing while undoing the implications from a redundant variable in SCIPshrinkDisjunctiveVarSet
3221- redundancy checks in SCIPnodeAddBoundinfer now take a possible change to an active variable into account
3222- fixed adding already added quadratic rows to NLP relaxation during solve
3223- fixed issue related to variable locks in the varbound constraint handler
3224- fixed bug in the quadratic constraint handler when changing infinite constraint sides
3225- fixed sorting of variables in linear constraint handler
3226- added additional checks to ensure numerical stability of dual proofs
3227- fixed a case when activities of a linear constraint got unreliable but where still used for reductions
3228- ensure that lhs <= rhs for linear constraints (without tolerances)
3229- make handling of read errors in SCIPfread() consistent between version with and without ZLIB
3230- correctly drop variable events in cons_indicator in restart
3231- fixed bug in cons_orbitope with upgrading of orbitope constraints
3232- additional checks in some presolvers for time limit being exceeded
3233- fixed bug in presolving of cons_varbound with multi-aggregated variables
3234- improve numerics in conflict analysis by using double-double arithmetic
3235- fixed bound acceptance condition to avoid inconsistencies
3236- fixed numerics in pseudoobj propagator by using double-double arithmetic
3237
3238Miscellaneous
3239-------------
3240
3241- modified display column for memory usage ("mem"), which reports the memory usage most of the time, but shows the creator name
3242 (heuristic, relaxation handler, LP relaxation, strong branching, pseudo solution) of every new incumbent solution. Together with this change,
3243 heuristic display characters have been unified to represent the type of the heuristic
3244 (diving, Large neighborhood search, propagation, etc.), see also type_heur.h.
3245- added assert that ensures that the locks of a variable have been decreased to 0 when it is freed
3246- added more output for completing a partial solution
3247- checks in debug mode that clean buffer memory is really clean when being freed are now disabled by default
3248- don't compute symmetries if reoptimization is enabled
3249- prefer integral values when fixing an almost-fixed continuous variable in the trivial presolver
3250- changed the name of the variable that is added by the OSiL reader to represent the quadratic or nonlinear parts of the objective function
3251- SCIP_EXPORT is now defined as __attribute__((__visibility__("default"))) if GCC and no SCIP config header is used
3252
3253@page RN6 Release notes for SCIP 6
3254
3255@section RN602 SCIP 6.0.2
3256*************************
3257
3258Features
3259--------
3260
3261- The abspower constraint handler now passes more accurate convexity
3262 information to the NLP relaxation.
3263
3264Examples and applications
3265-------------------------
3266
3267- added parsing functionality for optcumulative constraints in CIP format
3268
3269Interface changes
3270-----------------
3271
3272### Interfaces to external software
3273
3274- Updated the Mosek LP solver interface to support Mosek 9.0.
3275
3276Build system
3277------------
3278
3279### Cmake
3280
3281- new target to 'doc' to build documentation
3282- ctests now fail if parameter file not found
3283- add flag STATIC_GMP and improve GMP find module
3284- remove non-API functions from library (API functions use new macro SCIP_EXPORT)
3285- increase minimal required CMake version to 3.3
3286- correct paths and dependency information when installing SCIP
3287
3288Fixed bugs
3289----------
3290- fixed SCIP-Jack presolving bug that could lead to wrong results for Steiner arborescence problems
3291- fixed wrong unboundedness result in case not all constraints were already in the LP and enforcement was
3292 skipped because an optimal solution was found
3293- fixed wrong enforcement of constraints in the disjunction constraint handler
3294- fixed wrong behavior of concurrent solve ignoring initial solutions
3295- fixed bug in concurrent solve when problem was already solved in presolving
3296- aggregate non-artificial integer variable for XOR constraints with two binary variables and delete constraint
3297- copy the objective offset when copying the original problem
3298- fixed bug in SCIPlpiGetBInvARow in lpi_cpx using wrong size of resulting vector
3299- fixed quadratic runtime behavior in sepa_aggregation
3300- fixed statistics of separators
3301- improve numerical stability in varbound constraint handler by using double-double arithmetic
3302- fixed bug in propagation of dual proofs
3303- fixed bugs that arise for multiaggregated indicator variables by disallowing multiaggregation for them
3304- improve numerical stability in SCIPcomputeBilinEnvelope* by using double-double arithmetic
3305- fixed bug related to releasing pending bound changes in tree.c
3306- set STD FENV_ACCESS pragma to on in code that changes floating-point rounding mode
3307- disable GCC optimizations in main interval arithmetic code to prevent wrong optimizations
3308- fixed wrong assert in cons_xor concerning the variable type
3309- fixed different behavior of SCIPisLbBetter and SCIPisUbBetter between having NDEBUG defined or not
3310- correctly handle bound disjunctions in symmetry detection
3311- fixed issue in reliability branching related to the LP error flag not being reset
3312- fixed treatment of near-infinite bounds in shiftandpropagate's problem transformation
3313- fixed handling of infinite values in SCIPcomputeHyperplaneThreePoints()
3314- fixed comparisons of infinite values in heur_intshifting.c and heur_shifting.c
3315- fixed bug related to updating unprocessed cuts in the cutpool
3316- fixed bug related to enabling quadratic constraints during `CONSINITLP`
3317- add missing SCIP_EXPORT for functions used by GCG
3318- fixed memory leak and wrong initialization for trival cases in cons_symresack.c
3319- fixed bug with upgrading to packing/partitioning orbitopes
3320- fixed bug with the status while upgrading in presol_symbreak.c
3321- fixed wrong stage while clearing the conflict store
3322- fixed behavior of SCIPfixVar() by setting infeasible pointer to TRUE if fixval lies outside variable domain
3323- allow tightenVar() in SCIP_STAGE_PROBLEM stage
3324- fixed bug in cumulative constraint handler when separating the LP solution
3325- fixed issues with integer overflow in cumulative constraint handler
3326- fixed bug where the convexity of Benders' decomposition subproblems was checked even when users defined subproblem
3327 solving methods. Now, as per the documentation, the user must explicitly state whether the subproblem is convex
3328- fixed wrong indexing in heur_dualval
3329- fixed issue with basis status in SoPlex LPi
3330
3331Miscellaneous
3332-------------
3333
3334- statistics now output primal/dual bounds if objective limit is reached
3335- memory check in debug mode is now disabled by default
3336- message is now provided to the user to inform that automatic Benders' auxiliary variable lower bound computations are
3337 not activated when user defined subproblem solving methods are present
3338- corrected documentation of the primalgap in SCIP; describe when it will be infinite
3339
3340@section RN601 SCIP 6.0.1
3341*************************
3342
3343Features
3344--------
3345
3346- when using a debug solution every (multi-)aggregation will be checked w.r.t. this solution
3347
3348Performance improvements
3349------------------------
3350
3351- try greedy solution first before solving knapsack exactly using dynamic programming in SCIPsolveKnapsackExactly,
3352 compute greedy solution by weighted median selection.
3353- don't consider implied redcost by default in the reduced cost propagator
3354
3355Interface changes
3356-----------------
3357
3358### Deleted and changed API functions and macros
3359
3360- The preprocessor macro NO_CONFIG_HEADER now needs to be defined when
3361 including SCIP header files from a SCIP build or installation that
3362 has been build via the Makefile-only build system.
3363
3364- The following preprocessor macros have been renamed:
3365 WITH_ZLIB to SCIP_WITH_ZLIB, WITH_GMP to SCIP_WITH_GMP, WITH_READLINE
3366 to SCIP_WITH_READLINE, NO_SIGACTION to SCIP_NO_SIGACTION, NO_STRTOK_R
3367 to SCIP_NO_STRTOK_R, ROUNDING_FE to SCIP_ROUNDING_FE, ROUNDING_FP to
3368 SCIP_ROUNDING_FP, ROUNDING_MS to SCIP_ROUNDING_MS. Note, however, that
3369 the names of macros NO_RAND_R and NO_STRERROR_R have not been changed
3370 so far.
3371
3372### New API functions
3373
3374- SCIPhashmapInsertInt(), SCIPhashmapSetImageInt(), and SCIPhashmapGetImageInt() to use integer values as images in hashmaps
3375
3376### Command line interface
3377
3378- warn about coefficients in MPS files with absolute value larger than SCIP's value for infinity
3379
3380### Changed parameters
3381
3382- default clock type for timing is now wallclock
3383
3384Unit tests
3385----------
3386
3387- added unit tests for exact knapsack solving and (weighted) median selection algorithms
3388
3389Build system
3390------------
3391
3392### Cmake
3393
3394- add missing GMP dependency when compiling with SYM=bliss
3395- add DL library when linking to CPLEX to avoid linker errors
3396- new config.h header defining the current build configuration, e.g. SCIP_WITH_GMP
3397
3398Fixed bugs
3399----------
3400
3401- fixed handling of weights in cons_sos1 and cons_sos2 (NULL pointer to weights)
3402- fixed handling of unbounded LPs in SCIP and in several LPIs; added heuristic method to guess solution
3403- the STO reader is capable of handling scenarios defined using lower case "rhs"
3404- fixed OPB reader for instances without explicit plus signs
3405- correct dual solution values for bound constraints
3406- fixed recognition of variable with only one lock in cons_bivariate, cons_quadratic, and cons_nonlinear
3407- fixed update of constraint violations in solution repair in cons_bivariate, cons_quadratic, and cons_nonlinear
3408- print error message and terminate if matrix entries of a column are not consecutive in mps format
3409- fixed incorrect handling of fixed variables when transfer of cuts from LNS heuristic for Benders' decomposition
3410- fix returning local infeasible status by Ipopt interface if Ipopt finds problem locally infeasible
3411- skip attempt to apply fixings in linear constraint handler during solving stage as LP rows cannot change anymore
3412- fixed bug when reading >= indicator constraints in MPS format
3413- fix issue with nodes without domain changes if we ran into solution limit in prop_orbitalfixing
3414- fixed unresolved reference to CppAD's microsoft_timer() function on builds with MS/Intel compilers on Windows
3415- ignore implications added through SCIPaddVarImplication() that are redundant to global bounds also in the
3416 special case of an implication between two binary variables; also, use implications instead of cliques in the case
3417 of a binary implied variable with nonbinary active representative
3418- fixed bug with aggregated variables that are aggregated in propagation of cons_sos1
3419- fixed some special cases in SCIPselect/SCIPselectWeighted methods
3420- relaxed too strict assertion in Zirounding heuristic
3421- fixed the upgrade routine to XOR constraints: aggregate integer variable if its coefficient has the wrong sign
3422- fixed handling of nonartificial parity variables when deleting redundant XOR constraints
3423- earlier deletion of trivial XOR constraints (at most 1 operator left)
3424- fixed wrong hashmap accesses and added sanity check for the correct hashmap type
3425- avoid copying of unbounded solutions from sub-SCIPs as those cannot be checked completely
3426- corrected the output of the first LP value in case of branch-and-price
3427- fixed possible integer overflow, which led to wrong conclusion of infeasibility, in energetic reasoning of cons_cumulative.c
3428
3429Miscellaneous
3430-------------
3431
3432- do not scale linear constraints to integral coefficients
3433
3434@section RN600 SCIP 6.0.0
3435*************************
3436
3437Features
3438--------
3439
3440- new diving heuristic farkasdiving that dives into the direction of the pseudosolution and tries to construct Farkas-proofs
3441- new diving heuristic conflictdiving that considers locks from conflict constraints
3442- restructuring of timing of symmetry computation that allows to add symmetry handling components within presolving
3443- `lp/checkstability` is properly implemented for SoPlex LPI (spx2)
3444- new branching rule lookahead that evaluates potential child and grandchild nodes to determine a branching decision
3445- limits on the number of presolving rounds a presolver (maxrounds) or propagator/constraint handler (maxprerounds)
3446 participates in are now compared to the number of calls of the particular presolving method, not the number of
3447 presolving rounds in general, anymore
3448- new miscellaneous methods for constraints that have a one-row linear representation in pub_misc_linear.h
3449- a Benders' decomposition framework has been added. This framework provides the functionality for a user to solve a
3450 decomposed problem using Benders' decomposition. The framework includes classical optimality and feasibility cuts,
3451 integer optimality cuts and no-good cuts.
3452- add statistic that presents the number of resolves for instable LPs
3453- new readers for stochastic programming problems in SMPS format (reader_sto.h, reader_smps.h)
3454
3455Performance improvements
3456------------------------
3457
3458- cuts generated from certain quadratic constraints with convex feasible region are now global
3459- performance improvements for Adaptive Large Neighborhood Search heur_alns.c
3460 + all neighborhoods now start conservatively from maximum fixing rate
3461 + new default parameter settings for bandit selection parameters
3462 + no adjustment of minimum improvement by default
3463- improved bound tightening for some quadratic equations
3464- constraint handler checking order for original solutions has been modified to check those with negative check priority
3465 that don't need constraints after all other constraint handlers and constraints have been checked
3466- deactivate gauge cuts
3467
3468Examples and applications
3469-------------------------
3470
3471- new example `brachistochrone` in CallableLibrary examples collection; this example implements a discretized model to
3472 obtain the trajectory associated with the shortest time to go from point A to B for a particle under gravity only
3473- new example `circlepacking` in CallableLibrary examples collection; this example models two problems about packing
3474 circles of given radii into a rectangle
3475- new price-and-branch application for the ringpacking problem
3476- new stochastic capacitated facility location example demonstrating the use of the Benders' decomposition framework
3477
3478Interface changes
3479-----------------
3480
3481### New and changed callbacks
3482
3483- added parameter locktype to `SCIP_DECL_CONSLOCK` callback to indicate the type of variable locks
3484
3485### Deleted and changed API functions
3486
3487- Symmetry:
3488 + removed function SCIPgetTimingSymmetry() in presol_symmetry.h since this presolver does not compute symmetries independent
3489 of other components anymore
3490 + additional argument `recompute` to SCIPgetGeneratorsSymmetry() to allow recomputation of symmetries
3491
3492- Random generators:
3493 + the seed of SCIPinitializeRandomSeed() is now an unsigned int
3494 + the seed of SCIPsetInitializeRandomSeed() is now an unsigned int and it returns an unsigned int
3495 + new parameter for SCIPcreateRandom() to specify whether the global random seed shift should be used in the creation of
3496 the random number generator
3497
3498- Miscellaneous:
3499 + additional arguments `preferrecent`, `decayfactor` and `avglim` to SCIPcreateBanditEpsgreedy() to choose between
3500 weights that are simple averages or higher weights for more recent observations (the previous default).
3501 The last two parameters are used for a finer control of the exponential decay.
3502 + functions SCIPintervalSolveUnivariateQuadExpression(), SCIPintervalSolveUnivariateQuadExpressionPositive(), and
3503 SCIPintervalSolveUnivariateQuadExpressionPositiveAllScalar() now take an additional argument to specify already
3504 existing bounds on x, providing an entire interval ([-infinity,infinity]) gives previous behavior
6599 - added writing for pip files (linear, quadratic, polynomial nonlinear, polynomial abspower, polynomial bivariate, and
6600 and constraints)
6601 - CIP format variable characters defined, e.g. `SCIP_VARTYPE_INTEGER_CHAR`
6602 - Improved support for wbo format for weighted PBO problems, IBM's xml-solution
6603 format and pip and zimpl format for polynomial mixed-integer programs
6604 - New reader for (standard) bounds on variables
6605 - Extended reader for CIP models to handle various new constraints, including all types of linear constraints
6606 - flatzinc reader is now capable to read cumulative constraints
6607 - changed opb(/wbo) reader which now creates pseudoboolean constraints instead of linear- and and-constraints, only a
6608 non-linear objective will create and-constraints inside the reader and while reading a wbo file the topcost constraint
6609 is created as well
6610 - added clock for determine the time for reading
6611 - added reader for variable bounds (reader_bnd.{c,h})
6612 - Removed method SCIPreadSol(); call solution reading via SCIPreadProb() which calls the solution reader for .sol files.
6613
6614- Nonlinear:
6615 - Major extensions for nonlinear CIP, new option for n-ary branching on nonlinear variables (within pseudocost branching rule)
6616 - added BETA version of constraint handler for nonlinear constraints (cons_nonlinear.{c,h}) to handle nonlinear
6617 equations given by algebraic expressions using operands like addition, multiplication, power, exp, log, bivariate
6618 nonlinear constraints; currently no trigonometric functions
6619 - added BETA version of constraint handler for bivariate nonlinear constraints (cons_bivariate.{c,h}) to compute tight
6620 estimators for 1-convex and convex-concave bivariate nonlinear functions (given as expression tree)
6621 - the gams writer can now write nonlinear, abspower and bivariate constraints
6622 - Extended writer for GAMS and pip format to write more types of nonlinear constraints
6623 - the pip and zimpl reader now create nonlinear constraints for polynomials of degree > 2
6624
6625- Presolving:
6626 - new dual presolving methods in cons_setppc and cons_logicor
6627 - new presolving step `removeConstraintsDueToNegCliques` in locigor constraint handler which updates logicor constraints
6628 to setppc constraints if a negated clique inside this constraint exist, by default is off
6629 - new presolving step in cons_knapsack (detectRedundantVars, deleteRedundantVars) which determines redundant variables
6630 in knapsack constraint with or without using clique information
6631 - cons_logicor is now able to replace all aggregated variables in presolving by there active or negation of an active
6632 variable counterpart
6633 - prop_pseudoobj is now working in presolving as well
6634 - implement presolving in exitpre() in cons_orbitope and cons_indicator
6635
6636- Propagators:
6637 - added counter for number calls and timing for resolve propagation calls for constraint handler and propagators
6638 - Propagators are now also called in node presolving
6639 - the probing presolver presol_probing.{c.h} is now a propagator prop_probing.{c,h}, all corresponding parameters moved as well
6640 - the redcost separator sepa_redcost.{c.h} is now a propagator prop_redcost.{c,h}, all corresponding parameters moved as well
6641 - outsourced propAndSolve() method in solve.c which calls domain propagation and solving of the lp and relaxation
6642
6643- Statistic:
6644 - solutions which are given by the user from the outside are now marked by `#` in the output
6645 - the `Solving Time` is now spitted into presolving, solving and reading time
6646 - Presolvers section has new column `AddCons` which states the number of added constraint
6647 - Constraints section has new column named \#ResProp which show the number of resolve propagation calls of certain
6648 constraint handler
6649 - Constraint Timing section has a new column \#ResProp which states the time spend in resolve propagation method of the
6650 constraint handler
6651 - improved output of propagators in display statistics
6652 - new section `Propagator Timing` which shows the time spend in different callbacks of the propagator
6653 - rearranged first two columns of Propagators section; \#Propagate and \#ResProp stating the number of call for
6654 propagation and resolve propagation; the Time column is moved into the new section Propagator Timings
6655 - Constraints section has new column named `MaxNumber` which the maximum number of active constraint of a certain
6656 constraint handler
6657 - added two columns `Time-0-It` and `Calls-0-It` in the LP section which states the number of LP call and time spend for
6658 solving LPs with zero iterations (only refactorization)
6659 - The display of statistics for presolvers, propagators, constraints and LP solving has changed.
6660
6661Performance improvements
6662------------------------
6663
6664- Reorganized filtering process of separation storage (allows adding cuts for different solutions)
6665- Improved presolving for various constraint handlers
6666- Improved propagation methods for variable bound constraints
6667- Improved performance for quadratic constraints
6668- performance improvements in prop_vbounds
6669- child selection rules now get also applied when the relaxation value is equal to the bound changed in branching
6670- added dual reduction to cons_cumulative.c
6671- for continuous variables, the pseudo costs update and the pscost branching rule now use the same strategies for
6672 updating the pseudo costs and estimating the improvement in the LP bound
6673- only perform probing if the variables are locked
6674- performance and memory consumption improvements in xmlparse.c
6675- Improved knapsack cover cuts
6676- avoid very long separation times of LEWIs in cons_knapsack for very large minimal covers
6677- used SCIPallocMemoryArray() instead of SCIPallocBlockMemoryArray() which leads to fewer memory consumption in
6678 getLiftingSequence() in cons_knapsack, also improved cache use bei using an extra array instead blockmemory chunks
6679- switched FASTMIP from 1 to 2 for CPLEX and changed default pricing rule back to steepest edge pricing instead of
6680 quickstart steepest edge pricing
6681- made sorting method more robust
6682- LNS heuristics now use SCIPcopy() by default
6683- considering inactive variables in undercover heuristic; limiting effort for solving covering problem
6684- if during probing mode the LP relaxation is solved from scratch, e.g., when calling the shiftandpropagate heuristic
6685 before root node solving, then we clear the resulting LP state, since it might be a bad starting basis for the next
6686 solve of the LP relaxation (controlled by new parameter `lp/clearinitialprobinglp`)
6687- included LP simplifier into SoPlex LP interface, applied when solving from scratch (lpi_spx.cpp)
6688- new presolving steps in varbound constraint handler, tightening bounds, coefficients, sides and pairwise presolving
6689
6690Interface changes
6691-----------------
6692
6693- Miscellaneous:
6694 - The emphasis setting types now distinguish between plugin-type specific parameter settings (default, aggressive, fast, off),
6695 which are changed by SCIPsetHeuristics/Presolving/Separating(), and global emphasis settings (default, cpsolver, easycip,
6696 feasibility, hardlp, optimality, counter), which can be set using SCIPsetEmphasis().
6697
6698### New and changed callbacks
6699
6700- added propagator timings `SCIP_PROPTIMING_BEFORELP`, `SCIP_PROPTIMING_DURINGLPLOOP` and `SCIP_PROPTIMING_AFTERLPLOOP` for
6701 all propagation callbacks (see propagators and constraint handlers) which lead to calling the propagation methods of a
6702 propagator before the lp is solved, during the lp loop and after the lp solving loop
6703
6704- Conflict Analysis:
6705 - Added parameter `separate` to conflict handler callback method SCIP_DECL_CONFLICTEXEC() that defines whether the conflict
6706 constraint should be separated or not.
6707
6708- Constraint Handler:
6709 - The new constraint handler callback SCIP_DECL_CONSDELVARS() is called after variables were marked for deletion.
6710 This method is optional and only of interest if you are using SCIP as a branch-and-price framework. That means,
6711 you are generating new variables during the search. If you are not doing that just define the function pointer
6712 to be `NULL`.
6713 If this method gets implemented you should iterate over all constraints of the constraint handler and delete all
6714 variables that were marked for deletion by SCIPdelVar().
6715
6716- NLP Solver Interface:
6717 - The callbacks SCIP_DECL_NLPIGETSOLUTION() and SCIP_DECL_NLPISETINITIALGUESS() got new parameters to get/set values of
6718 dual variables.
6719 - The callback SCIP_DECL_NLPICOPY() now passes the block memory of the target SCIP as an additional parameter.
6720
6721- Presolving:
6722 - New parameters `isunbounded` and `isinfeasible` for presolving initialization (SCIP_DECL_CONSINITPRE(),
6723 SCIP_DECL_PRESOLINITPRE(), SCIP_DECL_PROPINITPRE()) and presolving deinitialization (SCIP_DECL_CONSEXITPRE(),
6724 SCIP_DECL_PRESOLEXITPRE(), SCIP_DECL_PROPEXITPRE()) callbacks of presolvers,
6725 constraint handlers and propagators, telling the callback whether the problem was already declared to be
6726 unbounded or infeasible. This allows to avoid expensive steps in these methods in case the problem is already
6727 solved, anyway.
6728
6729 Note, that the C++ methods
6730 - scip::ObjConshdlr::scip_presol() corresponding to SCIP_DECL_CONSPRESOL()
6731 - scip::ObjConshdlr::scip_initpre() corresponding to SCIP_DECL_CONSINITPRE()
6732 - scip::ObjPresol::scip_initpre() corresponding to SCIP_DECL_PRESOLINITPRE()
6733 - scip::ObjProp::scip_initpre() corresponding to SCIP_DECL_PROPINITPRE()
6734 - scip::ObjConshdlr::scip_exitpre() corresponding to SCIP_DECL_CONSEXITPRE()
6735 - scip::ObjPresol::scip_exitpre() corresponding to SCIP_DECL_PRESOLEXITPRE()
6736 - scip::ObjProp::scip_exitpre() corresponding to and SCIP_DECL_PROPEXITPRE()
6737 are virtual functions. That means, if you are not adding the new parameters, your code will still compile, but these methods are not executed.
6738 - Propagators are now also called in during presolving, this is supported by the new callback methods SCIP_DECL_PROPINITPRE(),
6739 SCIP_DECL_PROPEXITPRE(), and SCIP_DECL_PROPPRESOL().
6740 - The new parameters `nnewaddconss` and `naddconss` were added to the constraint handler callback method SCIP_DECL_CONSPRESOL()
6741 and the presolver callback method SCIP_DECL_PRESOLEXEC(). These parameters were also added to corresponding C++ wrapper
6742 class methods (scip_presol() in objconshdlr.h and scip_exec() in objpresol.h)
6743
6744- Problem Data:
6745 - The callback SCIP_DECL_PROBCOPY() got a new parameter `global` to indicate whether the global problem or a local version is copied.
6746
6747### Deleted and changed API functions
6748
6749- implemented SCIPlpiGetPrimalRay() in SoPlex interface that has become available with SoPlex version 1.5.0.2
6750- allowed calling SCIPgetRowSolActivity() in `SCIP_STAGE_SOLVED`, since LP is still available
6751- various extensions and modifications for expressions and expression trees (too much to state here)
6752- The result value `SCIP_NEWROUND` has been added, it allows a separator/constraint handler to start a new separation round
6753 (without previous calls to other separators/conshdlrs).
6754- SCIPcalcNodeselPriority() got a new parameter `branchdir`, which defines the type of branching that was performed: upwards, downwards, or fixed.
6755
6756- Constraint Handlers:
6757 - Method SCIPincludeQuadconsUpgrade() of quadratic constraint handler got new parameter `active` to indicate whether the upgrading method is active by default.
6758 - Method SCIPseparateRelaxedKnapsack() in knapsack constraint handler got new parameter `cutoff`, which is a pointer to store whether a cutoff was found.
6759
6760- Nonlinear expressions, relaxation, and solver interface:
6761 - SCIPcreateNLPSol() now creates a `SCIP_SOL` that is linked to the solution of the current NLP relaxation
6762 - Various types and functions dealing with polynomial expressions have been renamed to use the proper terms `monomial` and
6763 `polynomial` in nonlinear expressions (nlpi/∗expr*); results in many renamings of types, structs and methods.
6764 - The methods SCIPnlpGetObjective(), SCIPnlpGetSolVals(), and SCIPnlpGetVarSolVal() have been removed, use SCIPgetNLPObjval(),
6765 SCIPvarGetNLPSol() and SCIPcreateNLPSol() to retrieve NLP solution values instead.
6766 SCIPcreateNLPSol() now returns an error if NLP or NLP solution is not available
6767 - Removed methods SCIPmarkRequireNLP() and SCIPisNLPRequired(), because the NLP is now always constructed if nonlinearities
6768 are present.
6769 - SCIPgetNLP() has been removed and NLP-methods from pub_nlp.h have been moved to scip.h, which resulted in some renamings, too.
6770 - renamed SCIPexprtreeEvalSol() to SCIPevalExprtreeSol() and now located in scip.h.
6771 - renamed SCIPexprtreeEvalIntLocalBounds() to SCIPevalExprtreeLocalBounds() and now located in scip.h.
6772 - renamed SCIPexprtreeEvalIntGlobalBounds() to SCIPevalExprtreeGlobalBounds() and now located in scip.h.
6773 - The functions SCIPnlpiGetSolution() and SCIPnlpiSetInitialGuess() got additional arguments to get/set dual values.
6774 - The method SCIPgetNLPI() got a new parameter `nlpiproblem`, which is a pointer to store the NLP solver interface problem.
6775
6776- Timing:
6777 - SCIPincludeProp() got additional parameters to set the timing mask of the propagator and the new callbacks and parameters
6778 related to calling the propagator in presolving.
6779 - SCIPincludeConshdlr() got additional parameters to set the variable deletion callback function and the timing mask for
6780 propagation.
6781 - removed parameters timelimit and memorylimit from SCIPapplyRens()
6782 - The parameters `timelimit` and `memorylimit` were removed from SCIPapplyRens().
6783
6784- Problem Data:
6785 - The method SCIPcopyProb() got a new parameter `global` to indicate whether the global problem or a local version is copied.
6786
6787- Writing and Parsing Constraints:
6788 - The methods SCIPwriteVarName(), SCIPwriteVarsList(), and SCIPwriteVarsLinearsum() got a new boolean parameter `type`
6789 that indicates whether the variable type should be written or not.
6790 - The methods SCIPparseVarName() and SCIPparseVarsList() got a new output parameter `endptr` that is filled with the position
6791 where the parsing stopped.
6792 - The method SCIPwriteVarsList() got additionally a new parameter `delimiter` that defines the character which is used for delimitation.
6793
6794- Variables:
6795 - SCIPmarkDoNotMultaggrVar()/SCIPvarMarkDoNotMultaggr() now allow to mark negated and aggregated variables
6796 - SCIPgetVarCopy() got a new parameter `success` that will be FALSE if method is called after problem creation stage and no hash map is
6797 given or no image for the given variable is contained in the given hash map.
6798 - SCIPchgVarType() got an extra boolean parameter to store if infeasibility is recognized while upgrading a variable from continuous
6799 type to an integer type.
6800 - SCIPdelVar() got a new parameter `deleted`, which stores whether the variable was successfully marked to be deleted.
6801
6802### New API functions
6803
6804- information about the quality of the solution of an LP (currently the condition number of the basis matrix) can now be:
6805 + requested from the LPI (currently only available for CPLEX): methods SCIPlpiGetRealSolQuality() and
6806 + SCIPprintLPSolutionQuality() command display lpsolquality in interactive shell display column lpcond to show
6807 + estimate on condition number, if available
6808- SCIPround() and SCIPfeasRound() to round to nearest integer
6809- SCIPsortRealRealIntInt() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines in misc.c
6810- SCIPsortRealIntLong(), SCIPsortPtrPtrRealInt() and corresponding sorting/inserting/deleting methods in
6811 pub_misc.h and necessary defines in misc.c
6812- SCIPcomputeLPRelIntPoint() to compute relative interior point of the current LP
6813- SCIPstartSolvingTime() and SCIPstopSolvingTime() which can be used to start or stop the solving time clock
6814- SCIPstrToRealValue() and SCIPstrCopySection() in pub_misc.h; these methods can be used to convert a string
6815 into a `SCIP_Real` value and to copy a substring.
6816- SCIPgetBinvarRepresentatives() which gets binary variables that are equal to some given binary variables,
6817 and which are either active, fixed, or multi-aggregated, or the negated variables of active, fixed, or multi-aggregated variables
6818- SCIPhasPrimalRay() and SCIPgetPrimalRayVal() that return whether a primal ray is stored and which value a
6819 given variable has in the primal ray, respectively
6820- SCIPsetConsModifiable()
6821- SCIPsetParam() which is a generic parameter setter method, independent of the parameter type
6822- SCIPpropInitpre(), SCIPpropExitpre(), SCIPpropPresol() which initializes, exists and executes the presolving phase
6823- SCIProwGetAge() to access the age of a row (pub_lp.h/lp.c)
6824- SCIPsolGetOrigObj() in pub_sol.h which returns for a solution in the original problem space the objective value
6825- SCIPretransformSol() in scip.h that allows to retransform a solution to the original space
6826- SCIPlpiClearState() to LP interfaces for clearing basis information in the LP solver
6827- SCIPgetSubscipDepth() to access the depth of the current SCIP as a copied subproblem
6828- SCIPdebugAddSolVal() and SCIPdebugGetSolVal() to add/get values to/from a debug solution
6829- SCIPsepastoreRemoveInefficaciousCuts() to remove non-efficious cuts from the separation storage
6830
6831- Nodes:
6832 - SCIPnodeGetParent() to get parent node of a node
6833 - SCIPnodesSharePath() in pub_tree.h that determines whether two nodes are on the same leaf-root path
6834 - SCIPnodesGetCommonAncestor() in pub_tree.h that finds the common ancestor node for two given nodes
6835
6836- Read and Write:
6837 - SCIPgetReadingTime() which returns the time for reading in seconds
6838 - SCIPparseVarsLinearsum(), SCIPparseVarsPolynomial() and SCIPwriteVarsPolynomial() and for writing and
6839 parsing polynomials in constraint handler writing/parsing methods
6840
6841- Memory:
6842 - SCIPcreateMesshdlrPThreads() and SCIPfreeMesshdlrPThreads() for allocating and deleting necessary memory
6843 for message handlers for parallel pthread version
6844 - SCIPallocClearMemoryArray() and BMSallocClearMemoryArray() for allocating cleared memory arrays in scip.h and memory.h
6845
6846- Intervals:
6847 - SCIPintervalPowerScalarInverse() to solve an equation y = x^p for given bounds on y and scalar exponent p
6848 - SCIPintervalQuadBivar() to compute tight bounds on a bivariate quadratic form
6849 - SCIPintervalSolveBivariateQuadExpressionAllScalar() to compute tight bounds on the solutions of a bivariate quadratic equation
6850
6851- Variables:
6852 - SCIPcomputeVarCurrent{L,U}b{Local,Global}() to compute local or global lower or upper bounds of a
6853 multiaggregated variable from the bounds of the aggregation variables
6854 - SCIPbranchVarValNary() for n-ary variable branching
6855 - SCIPgetNegatedVars() which returns all negated variables for a given array of variables, if the negated
6856 variables are not existing yet, they will be created
6857 - SCIPgetNTotalVars() that returns the total number of created vars, icluding variables that were deleted in the meantime
6858 - SCIPvarGetHashkey(), SCIPvarIsHashkeyEq(), SCIPvarGetHashkeyVal() in pub_var.h which can be used for `SCIP_HASHTABLE` of variables
6859 - SCIPvarGetNBdchgInfosLb() and SCIPvarGetNBdchgInfosUb() in pub_var.h returning the number of lower or upper bound changes on the active path
6860 - SCIPvarGetBdchgInfoLb() and SCIPvarGetBdchgInfoUb() returning the bound change information at the given position
6861 - SCIPvarMarkDeletable() to mark a variable to be deletable completely from the problem (for
6862 branch-and-price); can only be called before the variable is added to the problem
6863 - SCIPvarMarkNotDeletable() that marks a variable to be non-deleteable (used within SCIP for forbidding
6864 deletion of variables contained in solution, LP bases, (multi)aggregation, ...)
6865 - SCIPvarIsDeletable() that returns whether a variable is marked to be deletable (each variable is per default non-deletable)
6866
6867- NLP:
6868 - SCIPgetNLPVarsNonlinearity() to get for each variable in the NLP the number of NLP rows in which this variable appears in a nonlinear way
6869 - SCIPnlrowGetDualsol(), SCIPgetNLPVarsLbDualsol(), SCIPgetNLPVarsUbDualsol() to retrieve dual values from an NLP solution
6870 - SCIPgetNLPFracVars() to get the fractional variables in an NLP solution
6871
6872- Propagator:
6873 - SCIPpropSetPresolPriority() which changes the presolving priority of a given propagator
1.15.0