1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 2 /* */ 3 /* This file is part of the program and library */ 4 /* SCIP --- Solving Constraint Integer Programs */ 5 /* */ 6 /* Copyright (C) 2002-2021 Konrad-Zuse-Zentrum */ 7 /* fuer Informationstechnik Berlin */ 8 /* */ 9 /* SCIP is distributed under the terms of the ZIB Academic License. */ 10 /* */ 11 /* You should have received a copy of the ZIB Academic License */ 12 /* along with SCIP; see the file COPYING. If not visit scipopt.org. */ 13 /* */ 14 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 15 16 /**@file presol_gateextraction.h 17 * @ingroup PRESOLVERS 18 * @brief gateextraction presolver 19 * @author Michael Winkler 20 */ 21 22 /* This presolver tries to extract gate-constraints meaning and-constraints and set-partitioning constraints (and could 23 * be expanded to find xor-constraints too). This is done by detecting linearizations or systems of inequalities which 24 * form an and-constraint or a set-partitioning constraint. An example: 25 * 26 * we have a logicor constraint of the form: x + y + z >= 1 27 * 28 * and we also have the following set-packing constraints: (x + y <= 1 and x + z <= 1) <=> (~x + ~y >= 1 and ~x + ~z >= 1) 29 * 30 * - these three constraints form an and-constraint: x = ~y * ~z (x = AND(~y,~z)) 31 * 32 * if an additional set-packing constraint exists: y + z <= 1 33 * 34 * - these four constraints form a set-partitioning cons.: x + y + z = 1 35 * 36 * some information can be found: 37 * 38 * http://www.cs.ubc.ca/~hutter/earg/papers07/cnf-structure.pdf 39 * http://www.cadence.com/cn/cadence/cadence_labs/Documents/niklas_SAT_2005_Effective.pdf 40 * 41 * We also do some check for logicor and set-packing/-partitioning constraint with the same variables to upgrade these 42 * both constraints into one. For example: 43 * 44 * x + y + z >= 1 and x + y + z <= 1 form x + y + z = 1 45 * 46 */ 47 48 49 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/ 50 51 #ifndef __SCIP_PRESOL_GATEEXTRACTION_H__ 52 #define __SCIP_PRESOL_GATEEXTRACTION_H__ 53 54 #include "scip/def.h" 55 #include "scip/type_retcode.h" 56 #include "scip/type_scip.h" 57 58 #ifdef __cplusplus 59 extern "C" { 60 #endif 61 62 /** creates the gateextraction presolver and includes it in SCIP 63 * 64 * @ingroup PresolverIncludes 65 */ 66 SCIP_EXPORT 67 SCIP_RETCODE SCIPincludePresolGateextraction( 68 SCIP* scip /**< SCIP data structure */ 69 ); 70 71 #ifdef __cplusplus 72 } 73 #endif 74 75 #endif 76