1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 2 /* */ 3 /* This file is part of the program and library */ 4 /* SCIP --- Solving Constraint Integer Programs */ 5 /* */ 6 /* Copyright (c) 2002-2023 Zuse Institute Berlin (ZIB) */ 7 /* */ 8 /* Licensed under the Apache License, Version 2.0 (the "License"); */ 9 /* you may not use this file except in compliance with the License. */ 10 /* You may obtain a copy of the License at */ 11 /* */ 12 /* http://www.apache.org/licenses/LICENSE-2.0 */ 13 /* */ 14 /* Unless required by applicable law or agreed to in writing, software */ 15 /* distributed under the License is distributed on an "AS IS" BASIS, */ 16 /* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. */ 17 /* See the License for the specific language governing permissions and */ 18 /* limitations under the License. */ 19 /* */ 20 /* You should have received a copy of the Apache-2.0 license */ 21 /* along with SCIP; see the file LICENSE. If not visit scipopt.org. */ 22 /* */ 23 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 24 25 /**@file heur_locks.h 26 * @ingroup PRIMALHEURISTICS 27 * @brief locks primal heuristic 28 * @author Michael Winkler 29 * @author Gerald Gamrath 30 * 31 * The locks heuristic is a start heuristic that first tries to fix all binary variables, then solves the resulting LP 32 * and tries to round the solution and finally solves a sub-MIP on the remaining problem if the LP solution could not be 33 * rounded. The fixing works as follows: First, all variables are sorted by their total number of rounding locks (up- 34 * and down-locks summed up). Then, looking at the variable with the highest number of locks first, the variable is 35 * fixed to the bound where there are fewer locks (in case of ties, the bound which is better w.r.t. the objective 36 * function). This fix is propagated and the activities of all LP rows are updated. If any LP row becomes redundant 37 * w.r.t. the updated bounds, we adjust the rounding locks. 38 */ 39 40 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/ 41 42 #ifndef __SCIP_HEUR_LOCKS_H__ 43 #define __SCIP_HEUR_LOCKS_H__ 44 45 #include "scip/def.h" 46 #include "scip/type_heur.h" 47 #include "scip/type_retcode.h" 48 #include "scip/type_scip.h" 49 50 #ifdef __cplusplus 51 extern "C" { 52 #endif 53 54 /** creates the locks primal heuristic and includes it in SCIP 55 * 56 * @ingroup PrimalHeuristicIncludes 57 */ 58 SCIP_EXPORT 59 SCIP_RETCODE SCIPincludeHeurLocks( 60 SCIP* scip /**< SCIP data structure */ 61 ); 62 63 64 /** apply fix-and-propagate scheme based on variable locks 65 * 66 * @note probing mode of SCIP needs to be enabled before 67 */ 68 SCIP_EXPORT 69 SCIP_RETCODE SCIPapplyLockFixings( 70 SCIP* scip, /**< SCIP data structure */ 71 SCIP_HEURDATA* heurdata, /**< primal heuristic data */ 72 SCIP_Bool* cutoff, /**< pointer to store if a cutoff was detected */ 73 SCIP_Bool* allrowsfulfilled /**< pointer to store if all rows became redundant */ 74 ); 75 76 #ifdef __cplusplus 77 } 78 #endif 79 80 #endif 81