1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 2 /* */ 3 /* This file is part of the program and library */ 4 /* SCIP --- Solving Constraint Integer Programs */ 5 /* */ 6 /* Copyright (C) 2002-2021 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 visit scipopt.org. */ 13 /* */ 14 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 15 16 /**@file type_heur.h 17 * @ingroup TYPEDEFINITIONS 18 * @brief type definitions for primal heuristics 19 * @author Tobias Achterberg 20 * @author Timo Berthold 21 * 22 * This file defines the interface for primal heuristics implemented in C. 23 * 24 * - \ref HEUR "Instructions for implementing a primal heuristic" 25 * - \ref PRIMALHEURISTICS "List of available primal heuristics" 26 * - \ref scip::ObjHeur "C++ wrapper class" 27 */ 28 29 /** @defgroup DEFPLUGINS_HEUR Default Primal Heuristics 30 * @ingroup DEFPLUGINS 31 * @brief implementation files (.c files) of the default primal heuristics of SCIP 32 */ 33 34 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/ 35 36 #ifndef __SCIP_TYPE_HEUR_H__ 37 #define __SCIP_TYPE_HEUR_H__ 38 39 #include "scip/def.h" 40 #include "scip/type_scip.h" 41 #include "scip/type_result.h" 42 #include "scip/type_timing.h" 43 #include "scip/type_var.h" 44 45 #ifdef __cplusplus 46 extern "C" { 47 #endif 48 49 /** represents different methods for a dive set to explore the next children */ 50 #define SCIP_DIVETYPE_NONE 0x000u /**< no method specified */ 51 #define SCIP_DIVETYPE_INTEGRALITY 0x001u /**< use branching on a variable by shrinking the domain in the child nodes */ 52 #define SCIP_DIVETYPE_SOS1VARIABLE 0x002u /**< branch on a variable solution value by exploiting special-ordered set conflict structure */ 53 54 typedef unsigned int SCIP_DIVETYPE; 55 56 /** context for diving statistics */ 57 enum SCIP_DiveContext 58 { 59 SCIP_DIVECONTEXT_TOTAL = 0, /**< all contexts combined */ 60 SCIP_DIVECONTEXT_SINGLE = 1, /**< single heuristic context */ 61 SCIP_DIVECONTEXT_ADAPTIVE = 2 /**< within adaptive diving */ 62 }; 63 typedef enum SCIP_DiveContext SCIP_DIVECONTEXT; 64 65 66 typedef struct SCIP_Heur SCIP_HEUR; /**< primal heuristic */ 67 typedef struct SCIP_HeurData SCIP_HEURDATA; /**< locally defined primal heuristic data */ 68 typedef struct SCIP_Diveset SCIP_DIVESET; /**< common parameters for all diving heuristics */ 69 typedef struct SCIP_VGraph SCIP_VGRAPH; /**< variable graph data structure to determine breadth-first 70 * distances between variables */ 71 72 /** commonly used display characters indicating special classes of primal heuristics */ 73 #define SCIP_HEURDISPCHAR_LNS 'L' /**< a 'L'arge Neighborhood or other local search heuristic */ 74 #define SCIP_HEURDISPCHAR_DIVING 'd' /**< a 'd'iving heuristic that dives down an auxiliary branch-and-bound path */ 75 #define SCIP_HEURDISPCHAR_ITERATIVE 'i' /**< an iterative improvement heuristic such as 1-opt or 2-opt */ 76 #define SCIP_HEURDISPCHAR_OBJDIVING 'o' /**< an 'o'bjective diving or feasibility pump heuristic */ 77 #define SCIP_HEURDISPCHAR_PROP 'p' /**< a 'p'ropagation heuristic, often applied before branch-and-bound starts */ 78 #define SCIP_HEURDISPCHAR_ROUNDING 'r' /**< a 'r'ounding heuristic that iteratively tries to round an LP or relaxation solution */ 79 #define SCIP_HEURDISPCHAR_TRIVIAL 't' /**< a 't'rivial or helper heuristic, usually applied before branch-and-bound starts */ 80 81 /** copy method for heuristic plugins (called when SCIP copies plugins) 82 * 83 * input: 84 * - scip : SCIP main data structure 85 * - heur : the primal heuristic itself 86 */ 87 #define SCIP_DECL_HEURCOPY(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) 88 89 /** destructor of primal heuristic to free user data (called when SCIP is exiting) 90 * 91 * input: 92 * - scip : SCIP main data structure 93 * - heur : the primal heuristic itself 94 */ 95 #define SCIP_DECL_HEURFREE(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) 96 97 /** initialization method of primal heuristic (called after problem was transformed) 98 * 99 * input: 100 * - scip : SCIP main data structure 101 * - heur : the primal heuristic itself 102 */ 103 #define SCIP_DECL_HEURINIT(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) 104 105 /** deinitialization method of primal heuristic (called before transformed problem is freed) 106 * 107 * input: 108 * - scip : SCIP main data structure 109 * - heur : the primal heuristic itself 110 */ 111 #define SCIP_DECL_HEUREXIT(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) 112 113 /** solving process initialization method of primal heuristic (called when branch and bound process is about to begin) 114 * 115 * This method is called when the presolving was finished and the branch and bound process is about to begin. 116 * The primal heuristic may use this call to initialize its branch and bound specific data. 117 * 118 * input: 119 * - scip : SCIP main data structure 120 * - heur : the primal heuristic itself 121 */ 122 #define SCIP_DECL_HEURINITSOL(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) 123 124 /** solving process deinitialization method of primal heuristic (called before branch and bound process data is freed) 125 * 126 * This method is called before the branch and bound process is freed. 127 * The primal heuristic should use this call to clean up its branch and bound data. 128 * 129 * input: 130 * - scip : SCIP main data structure 131 * - heur : the primal heuristic itself 132 */ 133 #define SCIP_DECL_HEUREXITSOL(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) 134 135 /** execution method of primal heuristic 136 * 137 * Searches for feasible primal solutions. The method is called in the node processing loop. 138 * 139 * input: 140 * - scip : SCIP main data structure 141 * - heur : the primal heuristic itself 142 * - heurtiming : current point in the node solving loop 143 * - nodeinfeasible : was the current node already detected to be infeasible? 144 * - result : pointer to store the result of the heuristic call 145 * 146 * possible return values for *result: 147 * - SCIP_FOUNDSOL : at least one feasible primal solution was found 148 * - SCIP_DIDNOTFIND : the heuristic searched, but did not find a feasible solution 149 * - SCIP_DIDNOTRUN : the heuristic was skipped 150 * - SCIP_DELAYED : the heuristic was skipped, but should be called again as soon as possible, disregarding 151 * its frequency 152 */ 153 #define SCIP_DECL_HEUREXEC(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur, SCIP_HEURTIMING heurtiming, \ 154 SCIP_Bool nodeinfeasible, SCIP_RESULT* result) 155 156 157 /* callbacks for diving heuristic specific settings */ 158 159 /** calculate score and preferred rounding direction for the candidate variable; the best candidate maximizes the 160 * score 161 * 162 * input: 163 * - scip : SCIP main data structure 164 * - diveset : diving settings for scoring 165 * - divetype : represents different methods for a dive set to explore the next children 166 * - cand : candidate variable for which the score should be determined 167 * - candsol : solution value of variable in LP relaxation solution 168 * - candsfrac : fractional part of solution value of variable 169 * - score : pointer for diving score value - the best candidate maximizes this score 170 * - roundup : pointer to store whether the preferred rounding direction is upwards 171 * 172 * returns SCIP_OKAY if everything worked, otherwise, a suitable error code 173 */ 174 #define SCIP_DECL_DIVESETGETSCORE(x) SCIP_RETCODE x (SCIP* scip, SCIP_DIVESET* diveset, \ 175 SCIP_DIVETYPE divetype, SCIP_VAR* cand, SCIP_Real candsol, SCIP_Real candsfrac, SCIP_Real* score, SCIP_Bool* roundup) 176 177 /** 178 * optional callback to check preconditions for diving, e.g., if an incumbent solution is available 179 * 180 * input: 181 * - scip : SCIP main data structure 182 * - diveset : diving settings for scoring 183 * 184 * output: 185 * - available : TRUE if diveset can run, otherwise FALSE 186 * 187 * returns SCIP_OKAY if everything worked, otherwise, a suitable error code 188 */ 189 #define SCIP_DECL_DIVESETAVAILABLE(x) SCIP_RETCODE x (SCIP* scip, SCIP_DIVESET* diveset, SCIP_Bool* available) 190 191 #ifdef __cplusplus 192 } 193 #endif 194 195 #endif 196