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 (C) 2002-2017 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 email to scip@zib.de. */
13 /* */
14 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
15 
16 /**@file presol_implics.h
17  * @ingroup PRESOLVERS
18  * @brief implication graph presolver which checks for aggregations
19  * @author Tobias Achterberg
20  *
21  * This presolver looks for variable implications in \f$x == 0\f$ and \f$x == 1\f$ with the same implied variable.
22  * There are four possible cases:
23  * \f[
24  * x = 0 \Rightarrow y = lb,\; \mathrm{and}\; x = 1 \Rightarrow y = lb:\; \mathrm{fix}\; y\; \mathrm{to}\; lb
25  * \f]
26  * \f[
27  * x = 0 \Rightarrow y = lb,\; \mathrm{and}\; x = 1 \Rightarrow y = ub:\; \mathrm{aggregate}\; y == lb + (ub-lb)x
28  * \f]
29  * \f[
30  * x = 0 \Rightarrow y = ub,\; \mathrm{and}\; x = 1 \Rightarrow y = lb:\; \mathrm{aggregate}\; y == ub - (ub-lb)x
31  * \f]
32  * \f[
33  * x = 0 \Rightarrow y = ub,\; \mathrm{and}\; x = 1 \Rightarrow y = ub:\; \mathrm{fix}\; y\; \mathrm{to}\; ub
34  * \f]
35  */
36 
37 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
38 
39 #ifndef __SCIP_PRESOL_IMPLICS_H__
40 #define __SCIP_PRESOL_IMPLICS_H__
41 
42 
43 #include "scip/scip.h"
44 
45 #ifdef __cplusplus
46 extern "C" {
47 #endif
48 
49 /** creates the implics presolver and includes it in SCIP
50  *
51  * @ingroup PresolverIncludes
52  */
53 extern
55  SCIP* scip /**< SCIP data structure */
56  );
57 
58 #ifdef __cplusplus
59 }
60 #endif
61 
62 #endif
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:53
SCIP callable library.
SCIP_RETCODE SCIPincludePresolImplics(SCIP *scip)