/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /* */ /* This file is part of the program and library */ /* SCIP --- Solving Constraint Integer Programs */ /* */ /* Copyright 2002-2022 Zuse Institute Berlin */ /* */ /* Licensed under the Apache License, Version 2.0 (the "License"); */ /* you may not use this file except in compliance with the License. */ /* You may obtain a copy of the License at */ /* */ /* http://www.apache.org/licenses/LICENSE-2.0 */ /* */ /* Unless required by applicable law or agreed to in writing, software */ /* distributed under the License is distributed on an "AS IS" BASIS, */ /* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. */ /* See the License for the specific language governing permissions and */ /* limitations under the License. */ /* */ /* You should have received a copy of the Apache-2.0 license */ /* along with SCIP; see the file LICENSE. If not visit scipopt.org. */ /* */ /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /**@file type_heur.h * @ingroup TYPEDEFINITIONS * @brief type definitions for primal heuristics * @author Tobias Achterberg * @author Timo Berthold * * This file defines the interface for primal heuristics implemented in C. * * - \ref HEUR "Instructions for implementing a primal heuristic" * - \ref PRIMALHEURISTICS "List of available primal heuristics" * - \ref scip::ObjHeur "C++ wrapper class" */ /** @defgroup DEFPLUGINS_HEUR Default Primal Heuristics * @ingroup DEFPLUGINS * @brief implementation files (.c files) of the default primal heuristics of SCIP */ /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/ #ifndef __SCIP_TYPE_HEUR_H__ #define __SCIP_TYPE_HEUR_H__ #include "scip/def.h" #include "scip/type_scip.h" #include "scip/type_result.h" #include "scip/type_timing.h" #include "scip/type_var.h" #ifdef __cplusplus extern "C" { #endif /** represents different methods for a dive set to explore the next children */ #define SCIP_DIVETYPE_NONE 0x000u /**< no method specified */ #define SCIP_DIVETYPE_INTEGRALITY 0x001u /**< use branching on a variable by shrinking the domain in the child nodes */ #define SCIP_DIVETYPE_SOS1VARIABLE 0x002u /**< branch on a variable solution value by exploiting special-ordered set conflict structure */ typedef unsigned int SCIP_DIVETYPE; /** context for diving statistics */ enum SCIP_DiveContext { SCIP_DIVECONTEXT_TOTAL = 0, /**< all contexts combined */ SCIP_DIVECONTEXT_SINGLE = 1, /**< single heuristic context */ SCIP_DIVECONTEXT_ADAPTIVE = 2 /**< within adaptive diving */ }; typedef enum SCIP_DiveContext SCIP_DIVECONTEXT; typedef struct SCIP_Heur SCIP_HEUR; /**< primal heuristic */ typedef struct SCIP_HeurData SCIP_HEURDATA; /**< locally defined primal heuristic data */ typedef struct SCIP_Diveset SCIP_DIVESET; /**< common parameters for all diving heuristics */ typedef struct SCIP_VGraph SCIP_VGRAPH; /**< variable graph data structure to determine breadth-first * distances between variables */ /** commonly used display characters indicating special classes of primal heuristics */ #define SCIP_HEURDISPCHAR_LNS 'L' /**< a 'L'arge Neighborhood or other local search heuristic */ #define SCIP_HEURDISPCHAR_DIVING 'd' /**< a 'd'iving heuristic that dives down an auxiliary branch-and-bound path */ #define SCIP_HEURDISPCHAR_ITERATIVE 'i' /**< an iterative improvement heuristic such as 1-opt or 2-opt */ #define SCIP_HEURDISPCHAR_OBJDIVING 'o' /**< an 'o'bjective diving or feasibility pump heuristic */ #define SCIP_HEURDISPCHAR_PROP 'p' /**< a 'p'ropagation heuristic, often applied before branch-and-bound starts */ #define SCIP_HEURDISPCHAR_ROUNDING 'r' /**< a 'r'ounding heuristic that iteratively tries to round an LP or relaxation solution */ #define SCIP_HEURDISPCHAR_TRIVIAL 't' /**< a 't'rivial or helper heuristic, usually applied before branch-and-bound starts */ /** copy method for heuristic plugins (called when SCIP copies plugins) * * input: * - scip : SCIP main data structure * - heur : the primal heuristic itself */ #define SCIP_DECL_HEURCOPY(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) /** destructor of primal heuristic to free user data (called when SCIP is exiting) * * input: * - scip : SCIP main data structure * - heur : the primal heuristic itself */ #define SCIP_DECL_HEURFREE(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) /** initialization method of primal heuristic (called after problem was transformed) * * input: * - scip : SCIP main data structure * - heur : the primal heuristic itself */ #define SCIP_DECL_HEURINIT(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) /** deinitialization method of primal heuristic (called before transformed problem is freed) * * input: * - scip : SCIP main data structure * - heur : the primal heuristic itself */ #define SCIP_DECL_HEUREXIT(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) /** solving process initialization method of primal heuristic (called when branch and bound process is about to begin) * * This method is called when the presolving was finished and the branch and bound process is about to begin. * The primal heuristic may use this call to initialize its branch and bound specific data. * * input: * - scip : SCIP main data structure * - heur : the primal heuristic itself */ #define SCIP_DECL_HEURINITSOL(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) /** solving process deinitialization method of primal heuristic (called before branch and bound process data is freed) * * This method is called before the branch and bound process is freed. * The primal heuristic should use this call to clean up its branch and bound data. * * input: * - scip : SCIP main data structure * - heur : the primal heuristic itself */ #define SCIP_DECL_HEUREXITSOL(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur) /** execution method of primal heuristic * * Searches for feasible primal solutions. The method is called in the node processing loop. * * input: * - scip : SCIP main data structure * - heur : the primal heuristic itself * - heurtiming : current point in the node solving loop * - nodeinfeasible : was the current node already detected to be infeasible? * - result : pointer to store the result of the heuristic call * * possible return values for *result: * - SCIP_FOUNDSOL : at least one feasible primal solution was found * - SCIP_DIDNOTFIND : the heuristic searched, but did not find a feasible solution * - SCIP_DIDNOTRUN : the heuristic was skipped * - SCIP_DELAYED : the heuristic was skipped, but should be called again as soon as possible, disregarding * its frequency */ #define SCIP_DECL_HEUREXEC(x) SCIP_RETCODE x (SCIP* scip, SCIP_HEUR* heur, SCIP_HEURTIMING heurtiming, \ SCIP_Bool nodeinfeasible, SCIP_RESULT* result) /* callbacks for diving heuristic specific settings */ /** calculate score and preferred rounding direction for the candidate variable; the best candidate maximizes the * score * * input: * - scip : SCIP main data structure * - diveset : diving settings for scoring * - divetype : represents different methods for a dive set to explore the next children * - cand : candidate variable for which the score should be determined * - candsol : solution value of variable in LP relaxation solution * - candsfrac : fractional part of solution value of variable * - score : pointer for diving score value - the best candidate maximizes this score * - roundup : pointer to store whether the preferred rounding direction is upwards * * returns SCIP_OKAY if everything worked, otherwise, a suitable error code */ #define SCIP_DECL_DIVESETGETSCORE(x) SCIP_RETCODE x (SCIP* scip, SCIP_DIVESET* diveset, \ SCIP_DIVETYPE divetype, SCIP_VAR* cand, SCIP_Real candsol, SCIP_Real candsfrac, SCIP_Real* score, SCIP_Bool* roundup) /** * optional callback to check preconditions for diving, e.g., if an incumbent solution is available * * input: * - scip : SCIP main data structure * - diveset : diving settings for scoring * * output: * - available : TRUE if diveset can run, otherwise FALSE * * returns SCIP_OKAY if everything worked, otherwise, a suitable error code */ #define SCIP_DECL_DIVESETAVAILABLE(x) SCIP_RETCODE x (SCIP* scip, SCIP_DIVESET* diveset, SCIP_Bool* available) #ifdef __cplusplus } #endif #endif