1    	/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
2    	/*                                                                           */
3    	/*                  This file is part of the program and library             */
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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15   	/*  distributed under the License is distributed on an "AS IS" BASIS,        */
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18   	/*  limitations under the License.                                           */
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   type_heur.h
26   	 * @ingroup TYPEDEFINITIONS
27   	 * @brief  type definitions for primal heuristics
28   	 * @author Tobias Achterberg
29   	 * @author Timo Berthold
30   	 *
31   	 *  This file defines the interface for primal heuristics implemented in C.
32   	 *
33   	 *  - \ref HEUR "Instructions for implementing a primal heuristic"
34   	 *  - \ref PRIMALHEURISTICS "List of available primal heuristics"
35   	 *  - \ref scip::ObjHeur "C++ wrapper class"
36   	 */
37   	
38   	/** @defgroup DEFPLUGINS_HEUR Default Primal Heuristics
39   	 *  @ingroup DEFPLUGINS
40   	 *  @brief implementation files (.c files) of the default primal heuristics of SCIP
41   	 */
42   	
43   	/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
44   	
45   	#ifndef __SCIP_TYPE_HEUR_H__
46   	#define __SCIP_TYPE_HEUR_H__
47   	
48   	#include "scip/def.h"
49   	#include "scip/type_scip.h"
50   	#include "scip/type_result.h"
51   	#include "scip/type_timing.h"
52   	#include "scip/type_var.h"
53   	
54   	#ifdef __cplusplus
55   	extern "C" {
56   	#endif
57   	
58   	/** represents different methods for a dive set to explore the next children */
59   	#define SCIP_DIVETYPE_NONE                0x000u  /**< no method specified */
60   	#define SCIP_DIVETYPE_INTEGRALITY         0x001u  /**< use branching on a variable by shrinking the domain in the child nodes */
61   	#define SCIP_DIVETYPE_SOS1VARIABLE        0x002u  /**< branch on a variable solution value by exploiting special-ordered set conflict structure */
62   	
63   	typedef unsigned int SCIP_DIVETYPE;
64   	
65   	/** context for diving statistics */
66   	enum SCIP_DiveContext
67   	{
68   	   SCIP_DIVECONTEXT_TOTAL  = 0,                   /**< all contexts combined */
69   	   SCIP_DIVECONTEXT_SINGLE = 1,                   /**< single heuristic context */
70   	   SCIP_DIVECONTEXT_ADAPTIVE = 2,                 /**< within adaptive diving */
71   	   SCIP_DIVECONTEXT_SCHEDULER = 3                 /**< within the scheduler heuristic */
72   	};
73   	typedef enum SCIP_DiveContext SCIP_DIVECONTEXT;
74   	
75   	
76   	typedef struct SCIP_Heur SCIP_HEUR;               /**< primal heuristic */
77   	typedef struct SCIP_HeurData SCIP_HEURDATA;       /**< locally defined primal heuristic data */
78   	typedef struct SCIP_Diveset SCIP_DIVESET;         /**< common parameters for all diving heuristics */
79   	typedef struct SCIP_VGraph SCIP_VGRAPH;           /**< variable graph data structure to determine breadth-first
80   	                                                    *  distances between variables */
81   	
82   	/** commonly used display characters indicating special classes of primal heuristics */
83   	#define SCIP_HEURDISPCHAR_LNS       'L'  /**< a 'L'arge Neighborhood or other local search heuristic */
84   	#define SCIP_HEURDISPCHAR_DIVING    'd'  /**< a 'd'iving heuristic that dives down an auxiliary branch-and-bound path */
85   	#define SCIP_HEURDISPCHAR_ITERATIVE 'i'  /**< an iterative improvement heuristic such as 1-opt or 2-opt */
86   	#define SCIP_HEURDISPCHAR_OBJDIVING 'o'  /**< an 'o'bjective diving or feasibility pump heuristic */
87   	#define SCIP_HEURDISPCHAR_PROP      'p'  /**< a 'p'ropagation heuristic, often applied before branch-and-bound starts */
88   	#define SCIP_HEURDISPCHAR_ROUNDING  'r'  /**< a 'r'ounding heuristic that iteratively tries to round an LP or relaxation solution */
89   	#define SCIP_HEURDISPCHAR_TRIVIAL   't'  /**< a 't'rivial or helper heuristic, usually applied before branch-and-bound starts */
90   	
91   	/** copy method for heuristic plugins (called when SCIP copies plugins)
92   	 *
93   	 *  input:
94   	 *  - scip            : SCIP main data structure
95   	 *  - heur            : the primal heuristic itself
96   	 */
97   	#define SCIP_DECL_HEURCOPY(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
98   	
99   	/** destructor of primal heuristic to free user data (called when SCIP is exiting)
100  	 *
101  	 *  input:
102  	 *  - scip            : SCIP main data structure
103  	 *  - heur            : the primal heuristic itself
104  	 */
105  	#define SCIP_DECL_HEURFREE(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
106  	
107  	/** initialization method of primal heuristic (called after problem was transformed)
108  	 *
109  	 *  input:
110  	 *  - scip            : SCIP main data structure
111  	 *  - heur            : the primal heuristic itself
112  	 */
113  	#define SCIP_DECL_HEURINIT(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
114  	
115  	/** deinitialization method of primal heuristic (called before transformed problem is freed)
116  	 *
117  	 *  input:
118  	 *  - scip            : SCIP main data structure
119  	 *  - heur            : the primal heuristic itself
120  	 */
121  	#define SCIP_DECL_HEUREXIT(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
122  	
123  	/** solving process initialization method of primal heuristic (called when branch and bound process is about to begin)
124  	 *
125  	 *  This method is called when the presolving was finished and the branch and bound process is about to begin.
126  	 *  The primal heuristic may use this call to initialize its branch and bound specific data.
127  	 *
128  	 *  input:
129  	 *  - scip            : SCIP main data structure
130  	 *  - heur            : the primal heuristic itself
131  	 */
132  	#define SCIP_DECL_HEURINITSOL(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
133  	
134  	/** solving process deinitialization method of primal heuristic (called before branch and bound process data is freed)
135  	 *
136  	 *  This method is called before the branch and bound process is freed.
137  	 *  The primal heuristic should use this call to clean up its branch and bound data.
138  	 *
139  	 *  input:
140  	 *  - scip            : SCIP main data structure
141  	 *  - heur            : the primal heuristic itself
142  	 */
143  	#define SCIP_DECL_HEUREXITSOL(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur)
144  	
145  	/** execution method of primal heuristic
146  	 *
147  	 *  Searches for feasible primal solutions. The method is called in the node processing loop.
148  	 *
149  	 *  input:
150  	 *  - scip            : SCIP main data structure
151  	 *  - heur            : the primal heuristic itself
152  	 *  - heurtiming      : current point in the node solving loop
153  	 *  - nodeinfeasible  : was the current node already detected to be infeasible?
154  	 *  - result          : pointer to store the result of the heuristic call
155  	 *
156  	 *  possible return values for *result:
157  	 *  - SCIP_FOUNDSOL   : at least one feasible primal solution was found
158  	 *  - SCIP_DIDNOTFIND : the heuristic searched, but did not find a feasible solution
159  	 *  - SCIP_DIDNOTRUN  : the heuristic was skipped
160  	 *  - SCIP_DELAYED    : the heuristic was skipped, but should be called again as soon as possible, disregarding
161  	 *                      its frequency
162  	 */
163  	#define SCIP_DECL_HEUREXEC(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur, SCIP_HEURTIMING heurtiming, \
164  	      SCIP_Bool nodeinfeasible, SCIP_RESULT* result)
165  	
166  	
167  	/* callbacks for diving heuristic specific settings */
168  	
169  	/** calculate score and preferred rounding direction for the candidate variable; the best candidate maximizes the
170  	 *  score
171  	 *
172  	 *  input:
173  	 *  - scip            : SCIP main data structure
174  	 *  - diveset         : diving settings for scoring
175  	 *  - divetype        : represents different methods for a dive set to explore the next children
176  	 *  - cand            : candidate variable for which the score should be determined
177  	 *  - candsol         : solution value of variable in LP relaxation solution
178  	 *  - candsfrac       : fractional part of solution value of variable
179  	 *  - score           : pointer for diving score value - the best candidate maximizes this score
180  	 *  - roundup         : pointer to store whether the preferred rounding direction is upwards
181  	 *
182  	 *  returns SCIP_OKAY if everything worked, otherwise, a suitable error code
183  	 */
184  	#define SCIP_DECL_DIVESETGETSCORE(x) SCIP_RETCODE x (SCIP* scip, SCIP_DIVESET* diveset, \
185  	   SCIP_DIVETYPE divetype, SCIP_VAR* cand, SCIP_Real candsol, SCIP_Real candsfrac, SCIP_Real* score, SCIP_Bool* roundup)
186  	
187  	/**
188  	 * optional callback to check preconditions for diving, e.g., if an incumbent solution is available
189  	 *
190  	 * input:
191  	 *  - scip            : SCIP main data structure
192  	 *  - diveset         : diving settings for scoring
193  	 *
194  	 * output:
195  	 *  - available       : TRUE if diveset can run, otherwise FALSE
196  	 *
197  	 *  returns SCIP_OKAY if everything worked, otherwise, a suitable error code
198  	 */
199  	#define SCIP_DECL_DIVESETAVAILABLE(x) SCIP_RETCODE x (SCIP* scip, SCIP_DIVESET* diveset, SCIP_Bool* available)
200  	
201  	#ifdef __cplusplus
202  	}
203  	#endif
204  	
205  	#endif
206