# SCIP

Solving Constraint Integer Programs

 presol_dualagg.h Go to the documentation of this file. 1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 2 /* */ 3 /* This file is part of the program and library */ 4 /* SCIP --- Solving Constraint Integer Programs */ 5 /* */ 6 /* Copyright (C) 2002-2015 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 email to scip@zib.de. */ 13 /* */ 14 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 15  16 /**@file presol_dualagg.h 17  * @brief aggregate variables by dual arguments 18  * @author Dieter Weninger 19  * 20  * This presolver looks for variables which could not be handled by 21  * duality fixing because of one up-/downlock. 22  * If the constraint which delivers the up-/downlock has 23  * a specific structure, we can aggregate the corresponding variable. 24  * 25  * In more detail (for a minimization problem and the case of only one uplock): 26  * 27  * Given a variable x_i with c_i <= 0 and only one up lock (originating from a constraint c), 28  * we are looking for a binary variable x_j such that: 29  * 1) if x_j = 0, constraint c can only be fulfilled for x_i = lb_i, and 30  * 2) if x_j = 1, constraint c becomes redundant and x_i can be dual-fixed to its upper bound ub_i 31  * (or vice versa). Then we can perform the following aggregation: x_i = lb_i + x_j (ub_i - lb_i). 32  * 33  * Similar arguments apply for the case of only one down lock and c_i >= 0. 34  */ 35  36 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/ 37  38 #ifndef __SCIP_PRESOL_DUALAGG_H__ 39 #define __SCIP_PRESOL_DUALAGG_H__ 40  41  42 #include "scip/scip.h" 43  44 #ifdef __cplusplus 45 extern "C" { 46 #endif 47  48 /** creates the dualagg presolver and includes it in SCIP */ 49 extern 51  SCIP* scip /**< SCIP data structure */ 52  ); 53  54 #ifdef __cplusplus 55 } 56 #endif 57  58 #endif SCIP_RETCODEenum SCIP_Retcode SCIP_RETCODEDefinition: type_retcode.h:53 SCIPincludePresolDualaggSCIP_RETCODE SCIPincludePresolDualagg(SCIP *scip) SCIPstruct Scip SCIPDefinition: type_scip.h:30 scip.hSCIP callable library. Generated on Wed Jul 22 2015 for SCIP Doxygen Documentation by doxygen (1.8.6) © 2024 by Zuse Institute Berlin (ZIB), Imprint designed with Bootstrap