# SCIP

Solving Constraint Integer Programs

presol_dualinfer.h
Go to the documentation of this file.
1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
2 /* */
3 /* This file is part of the program and library */
4 /* SCIP --- Solving Constraint Integer Programs */
5 /* */
7 /* fuer Informationstechnik Berlin */
8 /* */
10 /* */
12 /* along with SCIP; see the file COPYING. If not visit scipopt.org. */
13 /* */
14 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
15
16 /**@file presol_dualinfer.h
17  * @ingroup PRESOLVERS
18  * @brief dual inference presolver
19  * @author Dieter Weninger
20  * @author Patrick Gemander
21  *
22  * This presolver does bound strengthening on continuous variables (columns) for getting bounds on dual variables y.
23  * The bounds of the dual variables are then used to fix primal variables or change the side of constraints.
24  * For ranged rows one needs to decide which side (rhs or lhs) determines the equality.
25  *
26  * We distinguish two cases concerning complementary slackness:
27  * i) reduced cost fixing: c_j - sup_y(y^T A_{.j}) > 0 => x_j = l_j
28  * c_j - inf_y(y^T A_{.j}) < 0 => x_j = u_j
29  * ii) positive dual lower bound: y_i > 0 => A_{i.}x = b_i
30  *
31  * Further information on this presolving approach are given in
32  * Achterberg et al. "Presolve reductions in mixed integer programming"
33  * and for a two-column extension in
34  * Chen et al. "Two-row and two-column mixed-integer presolve using hasing-based pairing methods".
35  */
36
37 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
38
39 #ifndef __SCIP_PRESOL_DUALINFER_H__
40 #define __SCIP_PRESOL_DUALINFER_H__
41
42 #include "scip/def.h"
43 #include "scip/type_retcode.h"
44 #include "scip/type_scip.h"
45
46 #ifdef __cplusplus
47 extern "C" {
48 #endif
49
50 /** creates the dual inference presolver and includes it in SCIP
51  *
52  * @ingroup PresolverIncludes
53  */
54 SCIP_EXPORT
56  SCIP* scip /**< SCIP data structure */
57  );
58
59 #ifdef __cplusplus
60 }
61 #endif
62
63 #endif
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:54
type definitions for return codes for SCIP methods
type definitions for SCIP&#39;s main datastructure
SCIP_RETCODE SCIPincludePresolDualinfer(SCIP *scip)
common defines and data types used in all packages of SCIP