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_gateextraction.h 26 * @ingroup PRESOLVERS 27 * @brief gateextraction presolver 28 * @author Michael Winkler 29 */ 30 31 /* This presolver tries to extract gate-constraints meaning and-constraints and set-partitioning constraints (and could 32 * be expanded to find xor-constraints too). This is done by detecting linearizations or systems of inequalities which 33 * form an and-constraint or a set-partitioning constraint. An example: 34 * 35 * we have a logicor constraint of the form: x + y + z >= 1 36 * 37 * and we also have the following set-packing constraints: (x + y <= 1 and x + z <= 1) <=> (~x + ~y >= 1 and ~x + ~z >= 1) 38 * 39 * - these three constraints form an and-constraint: x = ~y * ~z (x = AND(~y,~z)) 40 * 41 * if an additional set-packing constraint exists: y + z <= 1 42 * 43 * - these four constraints form a set-partitioning cons.: x + y + z = 1 44 * 45 * some information can be found: 46 * 47 * http://www.cs.ubc.ca/~hutter/earg/papers07/cnf-structure.pdf 48 * http://www.cadence.com/cn/cadence/cadence_labs/Documents/niklas_SAT_2005_Effective.pdf 49 * 50 * We also do some check for logicor and set-packing/-partitioning constraint with the same variables to upgrade these 51 * both constraints into one. For example: 52 * 53 * x + y + z >= 1 and x + y + z <= 1 form x + y + z = 1 54 * 55 */ 56 57 58 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/ 59 60 #ifndef __SCIP_PRESOL_GATEEXTRACTION_H__ 61 #define __SCIP_PRESOL_GATEEXTRACTION_H__ 62 63 #include "scip/def.h" 64 #include "scip/type_retcode.h" 65 #include "scip/type_scip.h" 66 67 #ifdef __cplusplus 68 extern "C" { 69 #endif 70 71 /** creates the gateextraction presolver and includes it in SCIP 72 * 73 * @ingroup PresolverIncludes 74 */ 75 SCIP_EXPORT 76 SCIP_RETCODE SCIPincludePresolGateextraction( 77 SCIP* scip /**< SCIP data structure */ 78 ); 79 80 #ifdef __cplusplus 81 } 82 #endif 83 84 #endif 85