/* ios.h (integer optimization suite) */ /*********************************************************************** * This code is part of GLPK (GNU Linear Programming Kit). * Copyright (C) 2003-2018 Free Software Foundation, Inc. * Written by Andrew Makhorin . * * GLPK is free software: you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * GLPK is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public * License for more details. * * You should have received a copy of the GNU General Public License * along with GLPK. If not, see . ***********************************************************************/ #ifndef IOS_H #define IOS_H #include "prob.h" #if 1 /* 02/II-2018 */ #define NEW_LOCAL 1 #endif #if 1 /* 15/II-2018 */ #define NEW_COVER 1 #endif typedef struct IOSLOT IOSLOT; typedef struct IOSNPD IOSNPD; typedef struct IOSBND IOSBND; typedef struct IOSTAT IOSTAT; typedef struct IOSROW IOSROW; typedef struct IOSAIJ IOSAIJ; #ifdef NEW_LOCAL /* 02/II-2018 */ typedef glp_prob IOSPOOL; typedef GLPROW IOSCUT; #else typedef struct IOSPOOL IOSPOOL; typedef struct IOSCUT IOSCUT; #endif struct glp_tree { /* branch-and-bound tree */ int magic; /* magic value used for debugging */ DMP *pool; /* memory pool to store all IOS components */ int n; /* number of columns (variables) */ /*--------------------------------------------------------------*/ /* problem components corresponding to the original MIP and its LP relaxation (used to restore the original problem object on exit from the solver) */ int orig_m; /* number of rows */ unsigned char *orig_type; /* uchar orig_type[1+orig_m+n]; */ /* types of all variables */ double *orig_lb; /* double orig_lb[1+orig_m+n]; */ /* lower bounds of all variables */ double *orig_ub; /* double orig_ub[1+orig_m+n]; */ /* upper bounds of all variables */ unsigned char *orig_stat; /* uchar orig_stat[1+orig_m+n]; */ /* statuses of all variables */ double *orig_prim; /* double orig_prim[1+orig_m+n]; */ /* primal values of all variables */ double *orig_dual; /* double orig_dual[1+orig_m+n]; */ /* dual values of all variables */ double orig_obj; /* optimal objective value for LP relaxation */ /*--------------------------------------------------------------*/ /* branch-and-bound tree */ int nslots; /* length of the array of slots (enlarged automatically) */ int avail; /* index of the first free slot; 0 means all slots are in use */ IOSLOT *slot; /* IOSLOT slot[1+nslots]; */ /* array of slots: slot[0] is not used; slot[p], 1 <= p <= nslots, either contains a pointer to some node of the branch-and-bound tree, in which case p is used on API level as the reference number of corresponding subproblem, or is free; all free slots are linked into single linked list; slot[1] always contains a pointer to the root node (it is free only if the tree is empty) */ IOSNPD *head; /* pointer to the head of the active list */ IOSNPD *tail; /* pointer to the tail of the active list */ /* the active list is a doubly linked list of active subproblems which correspond to leaves of the tree; all subproblems in the active list are ordered chronologically (each a new subproblem is always added to the tail of the list) */ int a_cnt; /* current number of active nodes (including the current one) */ int n_cnt; /* current number of all (active and inactive) nodes */ int t_cnt; /* total number of nodes including those which have been already removed from the tree; this count is increased by one whenever a new node is created and never decreased */ /*--------------------------------------------------------------*/ /* problem components corresponding to the root subproblem */ int root_m; /* number of rows */ unsigned char *root_type; /* uchar root_type[1+root_m+n]; */ /* types of all variables */ double *root_lb; /* double root_lb[1+root_m+n]; */ /* lower bounds of all variables */ double *root_ub; /* double root_ub[1+root_m+n]; */ /* upper bounds of all variables */ unsigned char *root_stat; /* uchar root_stat[1+root_m+n]; */ /* statuses of all variables */ /*--------------------------------------------------------------*/ /* current subproblem and its LP relaxation */ IOSNPD *curr; /* pointer to the current subproblem (which can be only active); NULL means the current subproblem does not exist */ glp_prob *mip; /* original problem object passed to the solver; if the current subproblem exists, its LP segment corresponds to LP relaxation of the current subproblem; if the current subproblem does not exist, its LP segment corresponds to LP relaxation of the root subproblem (note that the root subproblem may differ from the original MIP, because it may be preprocessed and/or may have additional rows) */ unsigned char *non_int; /* uchar non_int[1+n]; */ /* these column flags are set each time when LP relaxation of the current subproblem has been solved; non_int[0] is not used; non_int[j], 1 <= j <= n, is j-th column flag; if this flag is set, corresponding variable is required to be integer, but its value in basic solution is fractional */ /*--------------------------------------------------------------*/ /* problem components corresponding to the parent (predecessor) subproblem for the current subproblem; used to inspect changes on freezing the current subproblem */ int pred_m; /* number of rows */ int pred_max; /* length of the following four arrays (enlarged automatically), pred_max >= pred_m + n */ unsigned char *pred_type; /* uchar pred_type[1+pred_m+n]; */ /* types of all variables */ double *pred_lb; /* double pred_lb[1+pred_m+n]; */ /* lower bounds of all variables */ double *pred_ub; /* double pred_ub[1+pred_m+n]; */ /* upper bounds of all variables */ unsigned char *pred_stat; /* uchar pred_stat[1+pred_m+n]; */ /* statuses of all variables */ /****************************************************************/ /* built-in cut generators segment */ IOSPOOL *local; /* local cut pool */ #if 1 /* 13/II-2018 */ glp_cov *cov_gen; /* pointer to working area used by the cover cut generator */ #endif glp_mir *mir_gen; /* pointer to working area used by the MIR cut generator */ glp_cfg *clq_gen; /* pointer to conflict graph used by the clique cut generator */ /*--------------------------------------------------------------*/ void *pcost; /* pointer to working area used on pseudocost branching */ int *iwrk; /* int iwrk[1+n]; */ /* working array */ double *dwrk; /* double dwrk[1+n]; */ /* working array */ /*--------------------------------------------------------------*/ /* control parameters and statistics */ const glp_iocp *parm; /* copy of control parameters passed to the solver */ double tm_beg; /* starting time of the search, in seconds; the total time of the search is the difference between xtime() and tm_beg */ double tm_lag; /* the most recent time, in seconds, at which the progress of the the search was displayed */ int sol_cnt; /* number of integer feasible solutions found */ #if 1 /* 11/VII-2013 */ void *P; /* glp_prob *P; */ /* problem passed to glp_intopt */ void *npp; /* NPP *npp; */ /* preprocessor workspace or NULL */ const char *save_sol; /* filename (template) to save every new solution */ int save_cnt; /* count to generate filename */ #endif /*--------------------------------------------------------------*/ /* advanced solver interface */ int reason; /* flag indicating the reason why the callback routine is being called (see glpk.h) */ int stop; /* flag indicating that the callback routine requires premature termination of the search */ int next_p; /* reference number of active subproblem selected to continue the search; 0 means no subproblem has been selected */ int reopt; /* flag indicating that the current LP relaxation needs to be re-optimized */ int reinv; /* flag indicating that some (non-active) rows were removed from the current LP relaxation, so if there no new rows appear, the basis must be re-factorized */ int br_var; /* the number of variable chosen to branch on */ int br_sel; /* flag indicating which branch (subproblem) is suggested to be selected to continue the search: GLP_DN_BRNCH - select down-branch GLP_UP_BRNCH - select up-branch GLP_NO_BRNCH - use general selection technique */ int child; /* subproblem reference number corresponding to br_sel */ }; struct IOSLOT { /* node subproblem slot */ IOSNPD *node; /* pointer to subproblem descriptor; NULL means free slot */ int next; /* index of another free slot (only if this slot is free) */ }; struct IOSNPD { /* node subproblem descriptor */ int p; /* subproblem reference number (it is the index to corresponding slot, i.e. slot[p] points to this descriptor) */ IOSNPD *up; /* pointer to the parent subproblem; NULL means this node is the root of the tree, in which case p = 1 */ int level; /* node level (the root node has level 0) */ int count; /* if count = 0, this subproblem is active; if count > 0, this subproblem is inactive, in which case count is the number of its child subproblems */ /* the following three linked lists are destroyed on reviving and built anew on freezing the subproblem: */ IOSBND *b_ptr; /* linked list of rows and columns of the parent subproblem whose types and bounds were changed */ IOSTAT *s_ptr; /* linked list of rows and columns of the parent subproblem whose statuses were changed */ IOSROW *r_ptr; /* linked list of rows (cuts) added to the parent subproblem */ int solved; /* how many times LP relaxation of this subproblem was solved; for inactive subproblem this count is always non-zero; for active subproblem, which is not current, this count may be non-zero, if the subproblem was temporarily suspended */ double lp_obj; /* optimal objective value to LP relaxation of this subproblem; on creating a subproblem this value is inherited from its parent; for the root subproblem, which has no parent, this value is initially set to -DBL_MAX (minimization) or +DBL_MAX (maximization); each time the subproblem is re-optimized, this value is appropriately changed */ double bound; /* local lower (minimization) or upper (maximization) bound for integer optimal solution to *this* subproblem; this bound is local in the sense that only subproblems in the subtree rooted at this node cannot have better integer feasible solutions; on creating a subproblem its local bound is inherited from its parent and then can be made stronger (never weaker); for the root subproblem its local bound is initially set to -DBL_MAX (minimization) or +DBL_MAX (maximization) and then improved as the root LP relaxation has been solved */ /* the following two quantities are defined only if LP relaxation of this subproblem was solved at least once (solved > 0): */ int ii_cnt; /* number of integer variables whose value in optimal solution to LP relaxation of this subproblem is fractional */ double ii_sum; /* sum of integer infeasibilities */ #if 1 /* 30/XI-2009 */ int changed; /* how many times this subproblem was re-formulated (by adding cutting plane constraints) */ #endif int br_var; /* ordinal number of branching variable, 1 <= br_var <= n, used to split this subproblem; 0 means that either this subproblem is active or branching was made on a constraint */ double br_val; /* (fractional) value of branching variable in optimal solution to final LP relaxation of this subproblem */ void *data; /* char data[tree->cb_size]; */ /* pointer to the application-specific data */ IOSNPD *temp; /* working pointer used by some routines */ IOSNPD *prev; /* pointer to previous subproblem in the active list */ IOSNPD *next; /* pointer to next subproblem in the active list */ }; struct IOSBND { /* bounds change entry */ int k; /* ordinal number of corresponding row (1 <= k <= m) or column (m+1 <= k <= m+n), where m and n are the number of rows and columns, resp., in the parent subproblem */ unsigned char type; /* new type */ double lb; /* new lower bound */ double ub; /* new upper bound */ IOSBND *next; /* pointer to next entry for the same subproblem */ }; struct IOSTAT { /* status change entry */ int k; /* ordinal number of corresponding row (1 <= k <= m) or column (m+1 <= k <= m+n), where m and n are the number of rows and columns, resp., in the parent subproblem */ unsigned char stat; /* new status */ IOSTAT *next; /* pointer to next entry for the same subproblem */ }; struct IOSROW { /* row (constraint) addition entry */ char *name; /* row name or NULL */ unsigned char origin; /* row origin flag (see glp_attr.origin) */ unsigned char klass; /* row class descriptor (see glp_attr.klass) */ unsigned char type; /* row type (GLP_LO, GLP_UP, etc.) */ double lb; /* row lower bound */ double ub; /* row upper bound */ IOSAIJ *ptr; /* pointer to the row coefficient list */ double rii; /* row scale factor */ unsigned char stat; /* row status (GLP_BS, GLP_NL, etc.) */ IOSROW *next; /* pointer to next entry for the same subproblem */ }; struct IOSAIJ { /* constraint coefficient */ int j; /* variable (column) number, 1 <= j <= n */ double val; /* non-zero coefficient value */ IOSAIJ *next; /* pointer to next coefficient for the same row */ }; #ifndef NEW_LOCAL /* 02/II-2018 */ struct IOSPOOL { /* cut pool */ int size; /* pool size = number of cuts in the pool */ IOSCUT *head; /* pointer to the first cut */ IOSCUT *tail; /* pointer to the last cut */ int ord; /* ordinal number of the current cut, 1 <= ord <= size */ IOSCUT *curr; /* pointer to the current cut */ }; #endif #ifndef NEW_LOCAL /* 02/II-2018 */ struct IOSCUT { /* cut (cutting plane constraint) */ char *name; /* cut name or NULL */ unsigned char klass; /* cut class descriptor (see glp_attr.klass) */ IOSAIJ *ptr; /* pointer to the cut coefficient list */ unsigned char type; /* cut type: GLP_LO: sum a[j] * x[j] >= b GLP_UP: sum a[j] * x[j] <= b GLP_FX: sum a[j] * x[j] = b */ double rhs; /* cut right-hand side */ IOSCUT *prev; /* pointer to previous cut */ IOSCUT *next; /* pointer to next cut */ }; #endif #define ios_create_tree _glp_ios_create_tree glp_tree *ios_create_tree(glp_prob *mip, const glp_iocp *parm); /* create branch-and-bound tree */ #define ios_revive_node _glp_ios_revive_node void ios_revive_node(glp_tree *tree, int p); /* revive specified subproblem */ #define ios_freeze_node _glp_ios_freeze_node void ios_freeze_node(glp_tree *tree); /* freeze current subproblem */ #define ios_clone_node _glp_ios_clone_node void ios_clone_node(glp_tree *tree, int p, int nnn, int ref[]); /* clone specified subproblem */ #define ios_delete_node _glp_ios_delete_node void ios_delete_node(glp_tree *tree, int p); /* delete specified subproblem */ #define ios_delete_tree _glp_ios_delete_tree void ios_delete_tree(glp_tree *tree); /* delete branch-and-bound tree */ #define ios_eval_degrad _glp_ios_eval_degrad void ios_eval_degrad(glp_tree *tree, int j, double *dn, double *up); /* estimate obj. degrad. for down- and up-branches */ #define ios_round_bound _glp_ios_round_bound double ios_round_bound(glp_tree *tree, double bound); /* improve local bound by rounding */ #define ios_is_hopeful _glp_ios_is_hopeful int ios_is_hopeful(glp_tree *tree, double bound); /* check if subproblem is hopeful */ #define ios_best_node _glp_ios_best_node int ios_best_node(glp_tree *tree); /* find active node with best local bound */ #define ios_relative_gap _glp_ios_relative_gap double ios_relative_gap(glp_tree *tree); /* compute relative mip gap */ #define ios_solve_node _glp_ios_solve_node int ios_solve_node(glp_tree *tree); /* solve LP relaxation of current subproblem */ #define ios_create_pool _glp_ios_create_pool IOSPOOL *ios_create_pool(glp_tree *tree); /* create cut pool */ #define ios_add_row _glp_ios_add_row int ios_add_row(glp_tree *tree, IOSPOOL *pool, const char *name, int klass, int flags, int len, const int ind[], const double val[], int type, double rhs); /* add row (constraint) to the cut pool */ #define ios_find_row _glp_ios_find_row IOSCUT *ios_find_row(IOSPOOL *pool, int i); /* find row (constraint) in the cut pool */ #define ios_del_row _glp_ios_del_row void ios_del_row(glp_tree *tree, IOSPOOL *pool, int i); /* remove row (constraint) from the cut pool */ #define ios_clear_pool _glp_ios_clear_pool void ios_clear_pool(glp_tree *tree, IOSPOOL *pool); /* remove all rows (constraints) from the cut pool */ #define ios_delete_pool _glp_ios_delete_pool void ios_delete_pool(glp_tree *tree, IOSPOOL *pool); /* delete cut pool */ #if 1 /* 11/VII-2013 */ #define ios_process_sol _glp_ios_process_sol void ios_process_sol(glp_tree *T); /* process integer feasible solution just found */ #endif #define ios_preprocess_node _glp_ios_preprocess_node int ios_preprocess_node(glp_tree *tree, int max_pass); /* preprocess current subproblem */ #define ios_driver _glp_ios_driver int ios_driver(glp_tree *tree); /* branch-and-bound driver */ #define ios_cov_gen _glp_ios_cov_gen void ios_cov_gen(glp_tree *tree); /* generate mixed cover cuts */ #define ios_pcost_init _glp_ios_pcost_init void *ios_pcost_init(glp_tree *tree); /* initialize working data used on pseudocost branching */ #define ios_pcost_branch _glp_ios_pcost_branch int ios_pcost_branch(glp_tree *T, int *next); /* choose branching variable with pseudocost branching */ #define ios_pcost_update _glp_ios_pcost_update void ios_pcost_update(glp_tree *tree); /* update history information for pseudocost branching */ #define ios_pcost_free _glp_ios_pcost_free void ios_pcost_free(glp_tree *tree); /* free working area used on pseudocost branching */ #define ios_feas_pump _glp_ios_feas_pump void ios_feas_pump(glp_tree *T); /* feasibility pump heuristic */ #if 1 /* 25/V-2013 */ #define ios_proxy_heur _glp_ios_proxy_heur void ios_proxy_heur(glp_tree *T); /* proximity search heuristic */ #endif #define ios_process_cuts _glp_ios_process_cuts void ios_process_cuts(glp_tree *T); /* process cuts stored in the local cut pool */ #define ios_choose_node _glp_ios_choose_node int ios_choose_node(glp_tree *T); /* select subproblem to continue the search */ #define ios_choose_var _glp_ios_choose_var int ios_choose_var(glp_tree *T, int *next); /* select variable to branch on */ #endif /* eof */