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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   	/*                                                                           */
12   	/*      http://www.apache.org/licenses/LICENSE-2.0                           */
13   	/*                                                                           */
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19   	/*                                                                           */
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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
64   	SCIP_RETCODE SCIPincludePresolImplics(
65   	   SCIP*                 scip                /**< SCIP data structure */
66   	   );
67   	
68   	#ifdef __cplusplus
69   	}
70   	#endif
71   	
72   	#endif
73