Scippy

SCIP

Solving Constraint Integer Programs

presol_implics.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 2002-2022 Zuse Institute Berlin */
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 */
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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_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
65  SCIP* scip /**< SCIP data structure */
66  );
67 
68 #ifdef __cplusplus
69 }
70 #endif
71 
72 #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
common defines and data types used in all packages of SCIP
SCIP_RETCODE SCIPincludePresolImplics(SCIP *scip)