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2    	/*                                                                           */
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4    	/*         SCIP --- Solving Constraint Integer Programs                      */
5    	/*                                                                           */
6    	/*  Copyright (c) 2002-2023 Zuse Institute Berlin (ZIB)                      */
7    	/*                                                                           */
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11   	/*                                                                           */
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13   	/*                                                                           */
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19   	/*                                                                           */
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22   	/*                                                                           */
23   	/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
24   	
25   	/**@file   presolve.h
26   	 * @ingroup PUBLICCOREAPI
27   	 * @brief  methods commonly used for presolving
28   	 * @author Michael Winkler
29   	 */
30   	
31   	/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
32   	
33   	#ifndef __SCIP_PRESOLVE_H__
34   	#define __SCIP_PRESOLVE_H__
35   	
36   	#include "scip/def.h"
37   	#include "scip/type_retcode.h"
38   	#include "scip/type_scip.h"
39   	#include "scip/type_var.h"
40   	
41   	#ifdef __cplusplus
42   	extern "C" {
43   	#endif
44   	
45   	/**@defgroup PublicSpecialPresolveMethods Special Methods
46   	 * @ingroup PublicPresolverMethods
47   	 * @brief methods commonly used for presolving
48   	 *
49   	 * @{
50   	 */
51   	/** try to reduce the necessary variable in a set of variables with corresponding bounds and boundtypes for which one
52   	 *  must be fulfilled
53   	 *
54   	 *  e.g. a set of logicor or bounddisjunctive constraint variables would be such a set
55   	 *
56   	 *  consider the following set:
57   	 *
58   	 *  x1 >= 1, x2 >= 3, x3 >= 1, x4 <= 0
59   	 *
60   	 *  by (global) implication data (cliques, implications, and variable bounds) we have also the following implications
61   	 *  given:
62   	 *
63   	 *  x1 >= 1 => x3 >= 1
64   	 *  x2 >= 2 => x3 >= 1
65   	 *  x4 <= 0 => x1 >= 1
66   	 *
67   	 *  Because of the last implication x4 is redundant, because x1 >= 1 would also be fulfilled in the variable set, so we
68   	 *  can reduce the set by x4.
69   	 *  Also, the both other implications and x3 >= 1 (in the given variable set) all imply exactly x3 >= 1, so we tighten
70   	 *  the global lower bound of x3 to 1 and the set of variables gets redundant.
71   	 */
72   	SCIP_EXPORT
73   	SCIP_RETCODE SCIPshrinkDisjunctiveVarSet(
74   	   SCIP*                 scip,               /**< SCIP data structure */
75   	   SCIP_VAR**            vars,               /**< variables array for which at least one must be fulfilled in the
76   	                                              *   following bounds and boundtypes */
77   	   SCIP_Real*            bounds,             /**< bounds array for which at least one must be fulfilled */
78   	   SCIP_Bool*            boundtypes,         /**< boundtypes array (TRUE == SCIP_BOUNDTYPE_UPPER, FALSE == SCIP_BOUNDTYPE_LOWER)
79   	                                              *   for which at least one must be fulfilled */
80   	   SCIP_Bool*            redundants,         /**< array which be filled and then indicate if a variable in the set is redundant */
81   	   int                   nvars,              /**< number of variables */
82   	   int*                  nredvars,           /**< pointer to store how many variables can be removed */
83   	   int*                  nglobalred,         /**< pointer to store number of global reductions on variable bounds found
84   	                                              *   through this set of variables */
85   	   SCIP_Bool*            setredundant,       /**< pointer to store if we found a global reduction on a variable which was part
86   	                                              *   of the given set of variables, this makes this disjunction redundant */
87   	   SCIP_Bool*            glbinfeas,          /**< pointer to store if global infeasibility was detected */
88   	   SCIP_Bool             fullshortening      /**< do we want to try the shortening procedure over the whole set (which might be expensive) */
89   	   );
90   	
91   	/** @} */
92   	
93   	#ifdef __cplusplus
94   	}
95   	#endif
96   	
97   	#endif
98