Scippy

SCIP

Solving Constraint Integer Programs

presol_gateextraction.h
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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 */
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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, */
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17 /* See the License for the specific language governing permissions and */
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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
77  SCIP* scip /**< SCIP data structure */
78  );
79 
80 #ifdef __cplusplus
81 }
82 #endif
83 
84 #endif
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:63
type definitions for return codes for SCIP methods
type definitions for SCIP&#39;s main datastructure
SCIP_RETCODE SCIPincludePresolGateextraction(SCIP *scip)
common defines and data types used in all packages of SCIP