SCIP
Solving Constraint Integer Programs
Solving Constraint Integer Programs
methods commonly used by primal heuristics
Modules | |
| Dive sets | |
| methods for dive sets to control the generic diving algorithm | |
Functions | |
| SCIP_RETCODE | SCIPperformGenericDivingAlgorithm (SCIP *scip, SCIP_DIVESET *diveset, SCIP_SOL *worksol, SCIP_HEUR *heur, SCIP_RESULT *result, SCIP_Bool nodeinfeasible) |
| SCIP_RETCODE | SCIPcopyLargeNeighborhoodSearch (SCIP *sourcescip, SCIP *subscip, SCIP_HASHMAP *varmap, const char *suffix, SCIP_VAR **fixedvars, SCIP_Real *fixedvals, int nfixedvars, SCIP_Bool uselprows, SCIP_Bool copycuts, SCIP_Bool *success, SCIP_Bool *valid) |
| SCIP_RETCODE SCIPperformGenericDivingAlgorithm | ( | SCIP * | scip, |
| SCIP_DIVESET * | diveset, | ||
| SCIP_SOL * | worksol, | ||
| SCIP_HEUR * | heur, | ||
| SCIP_RESULT * | result, | ||
| SCIP_Bool | nodeinfeasible | ||
| ) |
performs a diving within the limits of the diveset parameters
This method performs a diving according to the settings defined by the diving settings diveset; Contrary to the name, SCIP enters probing mode (not diving mode) and dives along a path into the tree. Domain propagation is applied at every node in the tree, whereas probing LPs might be solved less frequently.
Starting from the current LP solution, the algorithm selects candidates which maximize the score defined by the diveset and whose solution value has not yet been rendered infeasible by propagation, and propagates the bound change on this candidate.
The algorithm iteratively selects the the next (unfixed) candidate in the list, until either enough domain changes or the resolve frequency of the LP trigger an LP resolve (and hence, the set of potential candidates changes), or the last node is proven to be infeasible. It optionally backtracks and tries the other branching direction.
After the set of remaining candidates is empty or the targeted depth is reached, the node LP is solved, and the old candidates are replaced by the new LP candidates.
performs a diving within the limits of the diveset parameters
This method performs a diving according to the settings defined by the diving settings diveset; Contrary to the name, SCIP enters probing mode (not diving mode) and dives along a path into the tree. Domain propagation is applied at every node in the tree, whereas probing LPs might be solved less frequently.
Starting from the current LP solution, the algorithm selects candidates which maximize the score defined by the diveset and whose solution value has not yet been rendered infeasible by propagation, and propagates the bound change on this candidate.
The algorithm iteratively selects the the next (unfixed) candidate in the list, until either enough domain changes or the resolve frequency of the LP trigger an LP resolve (and hence, the set of potential candidates changes), or the last node is proven to be infeasible. It optionally backtracks and tries the other branching direction.
After the set of remaining candidates is empty or the targeted depth is reached, the node LP is solved, and the old candidates are replaced by the new LP candidates.
| scip | SCIP data structure |
| diveset | settings for diving |
| worksol | non-NULL working solution |
| heur | the calling primal heuristic |
| result | SCIP result pointer |
| nodeinfeasible | is the current node known to be infeasible? |
Definition at line 192 of file heuristics.c.
References FALSE, MAX, MIN, MINLPITER, NULL, SCIP_Bool, SCIP_BRANCHDIR_AUTO, SCIP_BRANCHDIR_DOWNWARDS, SCIP_BRANCHDIR_FIXED, SCIP_BRANCHDIR_UPWARDS, SCIP_CALL, SCIP_DELAYED, SCIP_DIDNOTFIND, SCIP_DIDNOTRUN, SCIP_FOUNDSOL, SCIP_INVALID, SCIP_INVALIDDATA, SCIP_Longint, SCIP_LPSOLSTAT_INFEASIBLE, SCIP_LPSOLSTAT_NOTSOLVED, SCIP_LPSOLSTAT_OBJLIMIT, SCIP_LPSOLSTAT_OPTIMAL, SCIP_MAXTREEDEPTH, SCIP_OKAY, SCIP_Real, SCIPABORT, SCIPallocBufferArray, SCIPbacktrackProbing(), SCIPceil(), SCIPchgVarLbProbing(), SCIPchgVarUbProbing(), SCIPdebugMsg, SCIPdivesetGetAvgQuot(), SCIPdivesetGetAvgQuotNoSol(), SCIPdivesetGetLPResolveDomChgQuot(), SCIPdivesetGetLPSolveFreq(), SCIPdivesetGetMaxLPIterOffset(), SCIPdivesetGetMaxLPIterQuot(), SCIPdivesetGetMaxRelDepth(), SCIPdivesetGetMinRelDepth(), SCIPdivesetGetName(), SCIPdivesetGetNCalls(), SCIPdivesetGetNLPIterations(), SCIPdivesetGetSolSuccess(), SCIPdivesetGetUbQuot(), SCIPdivesetGetUbQuotNoSol(), SCIPdivesetSetWorkSolution(), SCIPdivesetUseBacktrack(), SCIPdivesetUseOnlyLPBranchcands(), SCIPenableVarHistory(), SCIPendProbing(), SCIPerrorMessage, SCIPfindConshdlr(), SCIPfreeBufferArray, SCIPgetAvgDualbound(), SCIPgetAvgLowerbound(), SCIPgetCutoffbound(), SCIPgetDepth(), SCIPgetDiveBoundChangeData(), SCIPgetDualbound(), SCIPgetLastDivenode(), SCIPgetLowerbound(), SCIPgetLPBranchCands(), SCIPgetLPObjval(), SCIPgetLPSolstat(), SCIPgetMaxDepth(), SCIPgetNBestSolsFound(), SCIPgetNBinVars(), SCIPgetNIntVars(), SCIPgetNNodeLPIterations(), SCIPgetNNodes(), SCIPgetNSolsFound(), SCIPgetNSOS1Vars(), SCIPgetNVars(), SCIPgetProbingDepth(), SCIPgetSolOrigObj(), SCIPgetSolVal(), SCIPhasCurrentNodeLP(), SCIPheurGetName(), SCIPinfinity(), SCIPisFeasEQ(), SCIPisFeasGE(), SCIPisFeasGT(), SCIPisFeasLE(), SCIPisFeasLT(), SCIPisGE(), SCIPisLPSolBasic(), SCIPisLT(), SCIPisObjIntegral(), SCIPisStopped(), SCIPisZero(), SCIPlinkLPSol(), SCIPmakeIndicatorsFeasible(), SCIPmakeSOS1sFeasible(), SCIPnewProbingNode(), SCIPpropagateProbing(), SCIPreallocBufferArray, SCIPretransformObj(), SCIProundSol(), SCIPstartProbing(), SCIPtrySol(), SCIPunlinkSol(), SCIPupdateDivesetStats(), SCIPupdateVarPseudocost(), SCIPvarGetLbLocal(), SCIPvarGetName(), SCIPvarGetUbLocal(), SCIPvarMayRoundDown(), SCIPvarMayRoundUp(), selectNextDiving(), solveLP(), and TRUE.
| SCIP_RETCODE SCIPcopyLargeNeighborhoodSearch | ( | SCIP * | sourcescip, |
| SCIP * | subscip, | ||
| SCIP_HASHMAP * | varmap, | ||
| const char * | suffix, | ||
| SCIP_VAR ** | fixedvars, | ||
| SCIP_Real * | fixedvals, | ||
| int | nfixedvars, | ||
| SCIP_Bool | uselprows, | ||
| SCIP_Bool | copycuts, | ||
| SCIP_Bool * | success, | ||
| SCIP_Bool * | valid | ||
| ) |
get a sub-SCIP copy of the transformed problem
| sourcescip | source SCIP data structure |
| subscip | sub-SCIP used by the heuristic |
| varmap | a hashmap to store the mapping of source variables to the corresponding target variables |
| suffix | suffix for the problem name |
| fixedvars | source variables whose copies should be fixed in the target SCIP environment, or NULL |
| fixedvals | array of fixing values for target SCIP variables, or NULL |
| nfixedvars | number of source variables whose copies should be fixed in the target SCIP environment, or NULL |
| uselprows | should the linear relaxation of the problem defined by LP rows be copied? |
| copycuts | should cuts be copied (only if uselprows == FALSE) |
| success | was the copying successful? |
| valid | pointer to store whether the copying was valid, or NULL |
Definition at line 899 of file heuristics.c.
References createRows(), FALSE, NULL, SCIP_CALL, SCIP_MAXSTRLEN, SCIP_OKAY, SCIPcopyConsCompression(), SCIPcopyCuts(), SCIPcopyVars(), SCIPcreateProb(), SCIPgetProbName(), SCIPincludeDefaultPlugins(), SCIPsnprintf(), and TRUE.
Referenced by applyOfins(), SCIP_DECL_HEUREXEC(), SCIPapplyProximity(), and SCIPapplyRens().