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 event_shadowtree.c 26 * @ingroup DEFPLUGINS_EVENT 27 * @brief event handler for maintaining the unmodified branch-and-bound tree 28 * @author Jasper van Doornmalen 29 * 30 * It is possible that SCIP detects that variable bounds can be restricted globally further than formerly known. 31 * In that case, it is decided to update the global bounds of these variables, and modify the history of the branching 32 * decisions this way. This breaks methods that depend on the assumption that historic choices in the branch-and-bound 33 * tree remain unmodified througout the search, e.g., dynamic symmetry handling constraints. 34 * 35 * This event handler registers decisions made by the branch-and-bound tree directly at the moment of branching, and 36 * does not modify those at later stages of the solve. 37 */ 38 39 /*--+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/ 40 41 #ifndef __SCIP_EVENT_SHADOWTREE_H__ 42 #define __SCIP_EVENT_SHADOWTREE_H__ 43 44 #include "scip/def.h" 45 #include "scip/type_scip.h" 46 #include "scip/type_event.h" 47 #include "scip/type_tree.h" 48 #include "scip/type_var.h" 49 #include "scip/type_misc.h" 50 51 #ifdef __cplusplus 52 extern "C" { 53 #endif 54 55 /** bound change for branch-and-bound tree node in shadow tree */ 56 struct SCIP_ShadowBoundUpdate 57 { 58 SCIP_VAR* var; /**< changed variable */ 59 SCIP_Real newbound; /**< bound change */ 60 SCIP_BOUNDTYPE boundchgtype; /**< which bound of variable is changed (upper or lower) */ 61 }; 62 typedef struct SCIP_ShadowBoundUpdate SCIP_SHADOWBOUNDUPDATE; 63 64 /** branch-and-bound tree node for the shadowtree */ 65 struct SCIP_ShadowNode 66 { 67 SCIP_Longint nodeid; /**< ID of corresponding branch-and-bound tree node */ 68 struct SCIP_ShadowNode* parent; /**< parent of this shadowtree node. NULL iff it is the root node */ 69 struct SCIP_ShadowNode** children; /**< list of children of this shadowtree node. NULL iff it is a leaf */ 70 int nchildren; /**< number of elements in children 71 * 0 iff it is a leaf, -1 iff original node is DELETED */ 72 SCIP_SHADOWBOUNDUPDATE* branchingdecisions;/**< the variables branched on in this node. 73 * NULL iff nbranchingdecisions == 0 */ 74 int nbranchingdecisions;/**< the number of variables branched on in this node 75 * 0 iff branchingdecisions == NULL */ 76 SCIP_SHADOWBOUNDUPDATE* propagations; /**< the propagation (and branching decisions) updates in the node 77 * This is populated after branching with the propagations in that node. 78 * NULL iff npropagations == 0 */ 79 int npropagations; /**< the number of propagations. 0 iff propagations == NULL */ 80 }; 81 typedef struct SCIP_ShadowNode SCIP_SHADOWNODE; 82 83 /** shadow tree data structure */ 84 struct SCIP_ShadowTree 85 { 86 SCIP_HASHTABLE* nodemap; /**< pointer to the hashmap containing all shadow tree nodes */ 87 }; 88 typedef struct SCIP_ShadowTree SCIP_SHADOWTREE; 89 90 /** get the time spent in the shadow tree eventhdlr */ 91 SCIP_EXPORT 92 SCIP_Real SCIPgetShadowTreeEventHandlerExecutionTime( 93 SCIP* scip, /**< SCIP data structure */ 94 SCIP_EVENTHDLR* eventhdlr /**< event handler */ 95 ); 96 97 /** given a node number, returns the node in the shadow tree, or NULL if it doesn't exist */ 98 SCIP_EXPORT 99 SCIP_SHADOWNODE* SCIPshadowTreeGetShadowNodeFromNodeNumber( 100 SCIP_SHADOWTREE* shadowtree, /**< pointer to the shadow tree */ 101 SCIP_Longint nodeno /**< index of the node, equivalent to the standard branch-and-bound tree */ 102 ); 103 104 /** given a node, returns the node in the shadowtree, or NULL if it doesn't exist */ 105 SCIP_EXPORT 106 SCIP_SHADOWNODE* SCIPshadowTreeGetShadowNode( 107 SCIP_SHADOWTREE* shadowtree, /**< pointer to the shadow tree */ 108 SCIP_NODE* node /**< node from the actual branch-and-bound tree */ 109 ); 110 111 /** gets the shadow tree */ 112 SCIP_EXPORT 113 SCIP_SHADOWTREE* SCIPgetShadowTree( 114 SCIP_EVENTHDLR* eventhdlr /**< event handler */ 115 ); 116 117 /** activates shadow tree eventhandler if it is not already activated (which keeps a copy of the tree) */ 118 SCIP_EXPORT 119 SCIP_RETCODE SCIPactivateShadowTree( 120 SCIP* scip, /**< SCIP data structure */ 121 SCIP_EVENTHDLR* eventhdlr /**< event handler */ 122 ); 123 124 /** creates event handler for event */ 125 SCIP_EXPORT 126 SCIP_RETCODE SCIPincludeEventHdlrShadowTree( 127 SCIP* scip, /**< SCIP data structure */ 128 SCIP_EVENTHDLR** eventhdlrptr /**< pointer to store the event handler */ 129 ); 130 131 #ifdef __cplusplus 132 } 133 #endif 134 135 #endif 136