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 /* */ 8 /* Licensed under the Apache License, Version 2.0 (the "License"); */ 9 /* you may not use this file except in compliance with the License. */ 10 /* You may obtain a copy of the License at */ 11 /* */ 12 /* http://www.apache.org/licenses/LICENSE-2.0 */ 13 /* */ 14 /* Unless required by applicable law or agreed to in writing, software */ 15 /* distributed under the License is distributed on an "AS IS" BASIS, */ 16 /* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. */ 17 /* See the License for the specific language governing permissions and */ 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 heur_twoopt.h 26 * @ingroup PRIMALHEURISTICS 27 * @brief Primal heuristic to improve incumbent solution by flipping pairs of variables 28 * @author Timo Berthold 29 * @author Gregor Hendel 30 * 31 * The Twoopt heuristic attempts to improve a feasible MIP solution by altering the solution values of pairs of 32 * variables. Only variables which share a pre-defined ratio of LP rows are considered as pairs. Each step of the 33 * heuristic consists of improving the objective value by shifting one variable, and then compensating the resulting 34 * infeasibilities by shifting a second variable, without completely losing the objective improvement. Similarly to 35 * Oneopt (see @ref heur_oneopt.h), pairs are processed in non-decreasing order of their impact on the objective. 36 */ 37 38 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/ 39 40 #ifndef __SCIP_HEUR_TWOOPT_H__ 41 #define __SCIP_HEUR_TWOOPT_H__ 42 43 #include "scip/def.h" 44 #include "scip/type_retcode.h" 45 #include "scip/type_scip.h" 46 47 #ifdef __cplusplus 48 extern "C" { 49 #endif 50 51 /** creates the twoopt primal heuristic and includes it in SCIP 52 * 53 * @ingroup PrimalHeuristicIncludes 54 */ 55 SCIP_EXPORT 56 SCIP_RETCODE SCIPincludeHeurTwoopt( 57 SCIP* scip /**< SCIP data structure */ 58 ); 59 60 #ifdef __cplusplus 61 } 62 #endif 63 64 #endif 65