/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /* */ /* This file is part of the program and library */ /* SCIP --- Solving Constraint Integer Programs */ /* */ /* Copyright (C) 2002-2020 Konrad-Zuse-Zentrum */ /* fuer Informationstechnik Berlin */ /* */ /* SCIP is distributed under the terms of the ZIB Academic License. */ /* */ /* You should have received a copy of the ZIB Academic License */ /* along with SCIP; see the file COPYING. If not visit scipopt.org. */ /* */ /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /**@file cons_symresack.h * @ingroup CONSHDLRS * @brief constraint handler for symresack constraints * @author Christopher Hojny * */ /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/ #ifndef __SCIP_CONS_SYMRESACK_H__ #define __SCIP_CONS_SYMRESACK_H__ #include "scip/def.h" #include "scip/type_cons.h" #include "scip/type_retcode.h" #include "scip/type_scip.h" #include "scip/type_var.h" #ifdef __cplusplus extern "C" { #endif /** creates the handler for symresack constraints and includes it in SCIP * * @ingroup ConshdlrIncludes */ SCIP_EXPORT SCIP_RETCODE SCIPincludeConshdlrSymresack( SCIP* scip /**< SCIP data structure */ ); /**@addtogroup CONSHDLRS * * @{ * * @name Symresack Constraints * * @{ * * Given a permutation that acts on the order of the variables of a (mixed) 0/1-program * such that the permutation is a symmetry of the program, this constraint handler can * be used to handle the symmetries corresponding to the permutation. The symmetries * are handled by enforcing that a binary solution is lexicographically not smaller than * its permutation. In a presolving step, we check whether the permutation acts only on * binary points. Otherwise, we eliminate the non-binary variables from the permutation. * Furthermore, we delete fixed points from the permutation. * * Moreover, the constraint handler checks whether each cycle of the permutation is * contained in a set packing or partitioning constraint. In this case, the symresack * is strengthened to a ppsymresack and strong symmetry handling inequalities are added during * the initialization of the constraint handler. * * @pre The permutation is encoded by an array perm for which perm[i] = j if and only if * the image of i under the permutation is j. * * @pre The permutation given to the constraint handler has to be a symmetry of the * underlying problem. This is NOT checked by the constraint handler. */ /** creates a symmetry breaking constraint * * Depending on the given permutation, either an orbisack or symresack constraint * is created. */ SCIP_EXPORT SCIP_RETCODE SCIPcreateSymbreakCons( SCIP* scip, /**< SCIP data structure */ SCIP_CONS** cons, /**< pointer to hold the created constraint */ const char* name, /**< name of constraint */ int* perm, /**< permutation */ SCIP_VAR** vars, /**< variables */ int nvars, /**< number of variables in vars array */ SCIP_Bool ismodelcons, /**< whether the added constraint is a model constraint */ SCIP_Bool initial, /**< should the LP relaxation of constraint be in the initial LP? * Usually set to TRUE. Set to FALSE for 'lazy constraints'. */ SCIP_Bool separate, /**< should the constraint be separated during LP processing? * Usually set to TRUE. */ SCIP_Bool enforce, /**< should the constraint be enforced during node processing? * TRUE for model constraints, FALSE for additional, redundant constraints. */ SCIP_Bool check, /**< should the constraint be checked for feasibility? * TRUE for model constraints, FALSE for additional, redundant constraints. */ SCIP_Bool propagate, /**< should the constraint be propagated during node processing? * Usually set to TRUE. */ SCIP_Bool local, /**< is constraint only valid locally? * Usually set to FALSE. Has to be set to TRUE, e.g., for branching constraints. */ SCIP_Bool modifiable, /**< is constraint modifiable (subject to column generation)? * Usually set to FALSE. In column generation applications, set to TRUE if pricing * adds coefficients to this constraint. */ SCIP_Bool dynamic, /**< is constraint subject to aging? * Usually set to FALSE. Set to TRUE for own cuts which * are separated as constraints. */ SCIP_Bool removable, /**< should the relaxation be removed from the LP due to aging or cleanup? * Usually set to FALSE. Set to TRUE for 'lazy constraints' and 'user cuts'. */ SCIP_Bool stickingatnode /**< should the constraint always be kept at the node where it was added, even * if it may be moved to a more global node? * Usually set to FALSE. Set to TRUE to for constraints that represent node data. */ ); /** creates and captures a symresack constraint * * @note the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons() */ SCIP_EXPORT SCIP_RETCODE SCIPcreateConsSymresack( SCIP* scip, /**< SCIP data structure */ SCIP_CONS** cons, /**< pointer to hold the created constraint */ const char* name, /**< name of constraint */ int* perm, /**< permutation */ SCIP_VAR** vars, /**< variables */ int nvars, /**< number of variables in vars array */ SCIP_Bool ismodelcons, /**< whether the symresack is a model constraint */ SCIP_Bool initial, /**< should the LP relaxation of constraint be in the initial LP? * Usually set to TRUE. Set to FALSE for 'lazy constraints'. */ SCIP_Bool separate, /**< should the constraint be separated during LP processing? * Usually set to TRUE. */ SCIP_Bool enforce, /**< should the constraint be enforced during node processing? * TRUE for model constraints, FALSE for additional, redundant constraints. */ SCIP_Bool check, /**< should the constraint be checked for feasibility? * TRUE for model constraints, FALSE for additional, redundant constraints. */ SCIP_Bool propagate, /**< should the constraint be propagated during node processing? * Usually set to TRUE. */ SCIP_Bool local, /**< is constraint only valid locally? * Usually set to FALSE. Has to be set to TRUE, e.g., for branching constraints. */ SCIP_Bool modifiable, /**< is constraint modifiable (subject to column generation)? * Usually set to FALSE. In column generation applications, set to TRUE if pricing * adds coefficients to this constraint. */ SCIP_Bool dynamic, /**< is constraint subject to aging? * Usually set to FALSE. Set to TRUE for own cuts which * are separated as constraints. */ SCIP_Bool removable, /**< should the relaxation be removed from the LP due to aging or cleanup? * Usually set to FALSE. Set to TRUE for 'lazy constraints' and 'user cuts'. */ SCIP_Bool stickingatnode /**< should the constraint always be kept at the node where it was added, even * if it may be moved to a more global node? * Usually set to FALSE. Set to TRUE to for constraints that represent node data. */ ); /** creates and captures a symresack constraint * in its most basic variant, i.e., with all constraint flags set to their default values, which can be set * afterwards using SCIPsetConsFLAGNAME() in scip.h * * @see SCIPcreateConsSymresack() for the default constraint flag configuration * * @note the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons() */ SCIP_EXPORT SCIP_RETCODE SCIPcreateConsBasicSymresack( SCIP* scip, /**< SCIP data structure */ SCIP_CONS** cons, /**< pointer to hold the created constraint */ const char* name, /**< name of constraint */ int* perm, /**< permutation */ SCIP_VAR** vars, /**< variables */ int nvars, /**< number of variables in vars array */ SCIP_Bool ismodelcons /**< whether the symresack is a model constraint */ ); /** @} */ /** @} */ #ifdef __cplusplus } #endif #endif