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 presol_implics.h 26 * @ingroup PRESOLVERS 27 * @brief implication graph presolver which checks for aggregations 28 * @author Tobias Achterberg 29 * 30 * This presolver looks for variable implications in \f$x == 0\f$ and \f$x == 1\f$ with the same implied variable. 31 * There are four possible cases: 32 * \f[ 33 * x = 0 \Rightarrow y = lb,\; \mathrm{and}\; x = 1 \Rightarrow y = lb:\; \mathrm{fix}\; y\; \mathrm{to}\; lb 34 * \f] 35 * \f[ 36 * x = 0 \Rightarrow y = lb,\; \mathrm{and}\; x = 1 \Rightarrow y = ub:\; \mathrm{aggregate}\; y == lb + (ub-lb)x 37 * \f] 38 * \f[ 39 * x = 0 \Rightarrow y = ub,\; \mathrm{and}\; x = 1 \Rightarrow y = lb:\; \mathrm{aggregate}\; y == ub - (ub-lb)x 40 * \f] 41 * \f[ 42 * x = 0 \Rightarrow y = ub,\; \mathrm{and}\; x = 1 \Rightarrow y = ub:\; \mathrm{fix}\; y\; \mathrm{to}\; ub 43 * \f] 44 */ 45 46 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/ 47 48 #ifndef __SCIP_PRESOL_IMPLICS_H__ 49 #define __SCIP_PRESOL_IMPLICS_H__ 50 51 #include "scip/def.h" 52 #include "scip/type_retcode.h" 53 #include "scip/type_scip.h" 54 55 #ifdef __cplusplus 56 extern "C" { 57 #endif 58 59 /** creates the implics presolver and includes it in SCIP 60 * 61 * @ingroup PresolverIncludes 62 */ 63 SCIP_EXPORT 64 SCIP_RETCODE SCIPincludePresolImplics( 65 SCIP* scip /**< SCIP data structure */ 66 ); 67 68 #ifdef __cplusplus 69 } 70 #endif 71 72 #endif 73