diff -r d59bea55db9b -r c445c931472f src/glpios01.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/glpios01.c Mon Dec 06 13:09:21 2010 +0100 @@ -0,0 +1,1611 @@ +/* glpios01.c */ + +/*********************************************************************** +* This code is part of GLPK (GNU Linear Programming Kit). +* +* Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, +* 2009, 2010 Andrew Makhorin, Department for Applied Informatics, +* Moscow Aviation Institute, Moscow, Russia. All rights reserved. +* E-mail: . +* +* 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 . +***********************************************************************/ + +#include "glpios.h" + +/*********************************************************************** +* NAME +* +* ios_create_tree - create branch-and-bound tree +* +* SYNOPSIS +* +* #include "glpios.h" +* glp_tree *ios_create_tree(glp_prob *mip, const glp_iocp *parm); +* +* DESCRIPTION +* +* The routine ios_create_tree creates the branch-and-bound tree. +* +* Being created the tree consists of the only root subproblem whose +* reference number is 1. Note that initially the root subproblem is in +* frozen state and therefore needs to be revived. +* +* RETURNS +* +* The routine returns a pointer to the tree created. */ + +static IOSNPD *new_node(glp_tree *tree, IOSNPD *parent); + +glp_tree *ios_create_tree(glp_prob *mip, const glp_iocp *parm) +{ int m = mip->m; + int n = mip->n; + glp_tree *tree; + int i, j; + xassert(mip->tree == NULL); + mip->tree = tree = xmalloc(sizeof(glp_tree)); + tree->pool = dmp_create_pool(); + tree->n = n; + /* save original problem components */ + tree->orig_m = m; + tree->orig_type = xcalloc(1+m+n, sizeof(char)); + tree->orig_lb = xcalloc(1+m+n, sizeof(double)); + tree->orig_ub = xcalloc(1+m+n, sizeof(double)); + tree->orig_stat = xcalloc(1+m+n, sizeof(char)); + tree->orig_prim = xcalloc(1+m+n, sizeof(double)); + tree->orig_dual = xcalloc(1+m+n, sizeof(double)); + for (i = 1; i <= m; i++) + { GLPROW *row = mip->row[i]; + tree->orig_type[i] = (char)row->type; + tree->orig_lb[i] = row->lb; + tree->orig_ub[i] = row->ub; + tree->orig_stat[i] = (char)row->stat; + tree->orig_prim[i] = row->prim; + tree->orig_dual[i] = row->dual; + } + for (j = 1; j <= n; j++) + { GLPCOL *col = mip->col[j]; + tree->orig_type[m+j] = (char)col->type; + tree->orig_lb[m+j] = col->lb; + tree->orig_ub[m+j] = col->ub; + tree->orig_stat[m+j] = (char)col->stat; + tree->orig_prim[m+j] = col->prim; + tree->orig_dual[m+j] = col->dual; + } + tree->orig_obj = mip->obj_val; + /* initialize the branch-and-bound tree */ + tree->nslots = 0; + tree->avail = 0; + tree->slot = NULL; + tree->head = tree->tail = NULL; + tree->a_cnt = tree->n_cnt = tree->t_cnt = 0; + /* the root subproblem is not solved yet, so its final components + are unknown so far */ + tree->root_m = 0; + tree->root_type = NULL; + tree->root_lb = tree->root_ub = NULL; + tree->root_stat = NULL; + /* the current subproblem does not exist yet */ + tree->curr = NULL; + tree->mip = mip; + /*tree->solved = 0;*/ + tree->non_int = xcalloc(1+n, sizeof(char)); + memset(&tree->non_int[1], 0, n); + /* arrays to save parent subproblem components will be allocated + later */ + tree->pred_m = tree->pred_max = 0; + tree->pred_type = NULL; + tree->pred_lb = tree->pred_ub = NULL; + tree->pred_stat = NULL; + /* cut generator */ + tree->local = ios_create_pool(tree); + /*tree->first_attempt = 1;*/ + /*tree->max_added_cuts = 0;*/ + /*tree->min_eff = 0.0;*/ + /*tree->miss = 0;*/ + /*tree->just_selected = 0;*/ + tree->mir_gen = NULL; + tree->clq_gen = NULL; + /*tree->round = 0;*/ +#if 0 + /* create the conflict graph */ + tree->n_ref = xcalloc(1+n, sizeof(int)); + memset(&tree->n_ref[1], 0, n * sizeof(int)); + tree->c_ref = xcalloc(1+n, sizeof(int)); + memset(&tree->c_ref[1], 0, n * sizeof(int)); + tree->g = scg_create_graph(0); + tree->j_ref = xcalloc(1+tree->g->n_max, sizeof(int)); +#endif + /* pseudocost branching */ + tree->pcost = NULL; + tree->iwrk = xcalloc(1+n, sizeof(int)); + tree->dwrk = xcalloc(1+n, sizeof(double)); + /* initialize control parameters */ + tree->parm = parm; + tree->tm_beg = xtime(); + tree->tm_lag = xlset(0); + tree->sol_cnt = 0; + /* initialize advanced solver interface */ + tree->reason = 0; + tree->reopt = 0; + tree->reinv = 0; + tree->br_var = 0; + tree->br_sel = 0; + tree->child = 0; + tree->next_p = 0; + /*tree->btrack = NULL;*/ + tree->stop = 0; + /* create the root subproblem, which initially is identical to + the original MIP */ + new_node(tree, NULL); + return tree; +} + +/*********************************************************************** +* NAME +* +* ios_revive_node - revive specified subproblem +* +* SYNOPSIS +* +* #include "glpios.h" +* void ios_revive_node(glp_tree *tree, int p); +* +* DESCRIPTION +* +* The routine ios_revive_node revives the specified subproblem, whose +* reference number is p, and thereby makes it the current subproblem. +* Note that the specified subproblem must be active. Besides, if the +* current subproblem already exists, it must be frozen before reviving +* another subproblem. */ + +void ios_revive_node(glp_tree *tree, int p) +{ glp_prob *mip = tree->mip; + IOSNPD *node, *root; + /* obtain pointer to the specified subproblem */ + xassert(1 <= p && p <= tree->nslots); + node = tree->slot[p].node; + xassert(node != NULL); + /* the specified subproblem must be active */ + xassert(node->count == 0); + /* the current subproblem must not exist */ + xassert(tree->curr == NULL); + /* the specified subproblem becomes current */ + tree->curr = node; + /*tree->solved = 0;*/ + /* obtain pointer to the root subproblem */ + root = tree->slot[1].node; + xassert(root != NULL); + /* at this point problem object components correspond to the root + subproblem, so if the root subproblem should be revived, there + is nothing more to do */ + if (node == root) goto done; + xassert(mip->m == tree->root_m); + /* build path from the root to the current node */ + node->temp = NULL; + for (node = node; node != NULL; node = node->up) + { if (node->up == NULL) + xassert(node == root); + else + node->up->temp = node; + } + /* go down from the root to the current node and make necessary + changes to restore components of the current subproblem */ + for (node = root; node != NULL; node = node->temp) + { int m = mip->m; + int n = mip->n; + /* if the current node is reached, the problem object at this + point corresponds to its parent, so save attributes of rows + and columns for the parent subproblem */ + if (node->temp == NULL) + { int i, j; + tree->pred_m = m; + /* allocate/reallocate arrays, if necessary */ + if (tree->pred_max < m + n) + { int new_size = m + n + 100; + if (tree->pred_type != NULL) xfree(tree->pred_type); + if (tree->pred_lb != NULL) xfree(tree->pred_lb); + if (tree->pred_ub != NULL) xfree(tree->pred_ub); + if (tree->pred_stat != NULL) xfree(tree->pred_stat); + tree->pred_max = new_size; + tree->pred_type = xcalloc(1+new_size, sizeof(char)); + tree->pred_lb = xcalloc(1+new_size, sizeof(double)); + tree->pred_ub = xcalloc(1+new_size, sizeof(double)); + tree->pred_stat = xcalloc(1+new_size, sizeof(char)); + } + /* save row attributes */ + for (i = 1; i <= m; i++) + { GLPROW *row = mip->row[i]; + tree->pred_type[i] = (char)row->type; + tree->pred_lb[i] = row->lb; + tree->pred_ub[i] = row->ub; + tree->pred_stat[i] = (char)row->stat; + } + /* save column attributes */ + for (j = 1; j <= n; j++) + { GLPCOL *col = mip->col[j]; + tree->pred_type[mip->m+j] = (char)col->type; + tree->pred_lb[mip->m+j] = col->lb; + tree->pred_ub[mip->m+j] = col->ub; + tree->pred_stat[mip->m+j] = (char)col->stat; + } + } + /* change bounds of rows and columns */ + { IOSBND *b; + for (b = node->b_ptr; b != NULL; b = b->next) + { if (b->k <= m) + glp_set_row_bnds(mip, b->k, b->type, b->lb, b->ub); + else + glp_set_col_bnds(mip, b->k-m, b->type, b->lb, b->ub); + } + } + /* change statuses of rows and columns */ + { IOSTAT *s; + for (s = node->s_ptr; s != NULL; s = s->next) + { if (s->k <= m) + glp_set_row_stat(mip, s->k, s->stat); + else + glp_set_col_stat(mip, s->k-m, s->stat); + } + } + /* add new rows */ + if (node->r_ptr != NULL) + { IOSROW *r; + IOSAIJ *a; + int i, len, *ind; + double *val; + ind = xcalloc(1+n, sizeof(int)); + val = xcalloc(1+n, sizeof(double)); + for (r = node->r_ptr; r != NULL; r = r->next) + { i = glp_add_rows(mip, 1); + glp_set_row_name(mip, i, r->name); +#if 1 /* 20/IX-2008 */ + xassert(mip->row[i]->level == 0); + mip->row[i]->level = node->level; + mip->row[i]->origin = r->origin; + mip->row[i]->klass = r->klass; +#endif + glp_set_row_bnds(mip, i, r->type, r->lb, r->ub); + len = 0; + for (a = r->ptr; a != NULL; a = a->next) + len++, ind[len] = a->j, val[len] = a->val; + glp_set_mat_row(mip, i, len, ind, val); + glp_set_rii(mip, i, r->rii); + glp_set_row_stat(mip, i, r->stat); + } + xfree(ind); + xfree(val); + } +#if 0 + /* add new edges to the conflict graph */ + /* add new cliques to the conflict graph */ + /* (not implemented yet) */ + xassert(node->own_nn == 0); + xassert(node->own_nc == 0); + xassert(node->e_ptr == NULL); +#endif + } + /* the specified subproblem has been revived */ + node = tree->curr; + /* delete its bound change list */ + while (node->b_ptr != NULL) + { IOSBND *b; + b = node->b_ptr; + node->b_ptr = b->next; + dmp_free_atom(tree->pool, b, sizeof(IOSBND)); + } + /* delete its status change list */ + while (node->s_ptr != NULL) + { IOSTAT *s; + s = node->s_ptr; + node->s_ptr = s->next; + dmp_free_atom(tree->pool, s, sizeof(IOSTAT)); + } +#if 1 /* 20/XI-2009 */ + /* delete its row addition list (additional rows may appear, for + example, due to branching on GUB constraints */ + while (node->r_ptr != NULL) + { IOSROW *r; + r = node->r_ptr; + node->r_ptr = r->next; + xassert(r->name == NULL); + while (r->ptr != NULL) + { IOSAIJ *a; + a = r->ptr; + r->ptr = a->next; + dmp_free_atom(tree->pool, a, sizeof(IOSAIJ)); + } + dmp_free_atom(tree->pool, r, sizeof(IOSROW)); + } +#endif +done: return; +} + +/*********************************************************************** +* NAME +* +* ios_freeze_node - freeze current subproblem +* +* SYNOPSIS +* +* #include "glpios.h" +* void ios_freeze_node(glp_tree *tree); +* +* DESCRIPTION +* +* The routine ios_freeze_node freezes the current subproblem. */ + +void ios_freeze_node(glp_tree *tree) +{ glp_prob *mip = tree->mip; + int m = mip->m; + int n = mip->n; + IOSNPD *node; + /* obtain pointer to the current subproblem */ + node = tree->curr; + xassert(node != NULL); + if (node->up == NULL) + { /* freeze the root subproblem */ + int k; + xassert(node->p == 1); + xassert(tree->root_m == 0); + xassert(tree->root_type == NULL); + xassert(tree->root_lb == NULL); + xassert(tree->root_ub == NULL); + xassert(tree->root_stat == NULL); + tree->root_m = m; + tree->root_type = xcalloc(1+m+n, sizeof(char)); + tree->root_lb = xcalloc(1+m+n, sizeof(double)); + tree->root_ub = xcalloc(1+m+n, sizeof(double)); + tree->root_stat = xcalloc(1+m+n, sizeof(char)); + for (k = 1; k <= m+n; k++) + { if (k <= m) + { GLPROW *row = mip->row[k]; + tree->root_type[k] = (char)row->type; + tree->root_lb[k] = row->lb; + tree->root_ub[k] = row->ub; + tree->root_stat[k] = (char)row->stat; + } + else + { GLPCOL *col = mip->col[k-m]; + tree->root_type[k] = (char)col->type; + tree->root_lb[k] = col->lb; + tree->root_ub[k] = col->ub; + tree->root_stat[k] = (char)col->stat; + } + } + } + else + { /* freeze non-root subproblem */ + int root_m = tree->root_m; + int pred_m = tree->pred_m; + int i, j, k; + xassert(pred_m <= m); + /* build change lists for rows and columns which exist in the + parent subproblem */ + xassert(node->b_ptr == NULL); + xassert(node->s_ptr == NULL); + for (k = 1; k <= pred_m + n; k++) + { int pred_type, pred_stat, type, stat; + double pred_lb, pred_ub, lb, ub; + /* determine attributes in the parent subproblem */ + pred_type = tree->pred_type[k]; + pred_lb = tree->pred_lb[k]; + pred_ub = tree->pred_ub[k]; + pred_stat = tree->pred_stat[k]; + /* determine attributes in the current subproblem */ + if (k <= pred_m) + { GLPROW *row = mip->row[k]; + type = row->type; + lb = row->lb; + ub = row->ub; + stat = row->stat; + } + else + { GLPCOL *col = mip->col[k - pred_m]; + type = col->type; + lb = col->lb; + ub = col->ub; + stat = col->stat; + } + /* save type and bounds of a row/column, if changed */ + if (!(pred_type == type && pred_lb == lb && pred_ub == ub)) + { IOSBND *b; + b = dmp_get_atom(tree->pool, sizeof(IOSBND)); + b->k = k; + b->type = (unsigned char)type; + b->lb = lb; + b->ub = ub; + b->next = node->b_ptr; + node->b_ptr = b; + } + /* save status of a row/column, if changed */ + if (pred_stat != stat) + { IOSTAT *s; + s = dmp_get_atom(tree->pool, sizeof(IOSTAT)); + s->k = k; + s->stat = (unsigned char)stat; + s->next = node->s_ptr; + node->s_ptr = s; + } + } + /* save new rows added to the current subproblem */ + xassert(node->r_ptr == NULL); + if (pred_m < m) + { int i, len, *ind; + double *val; + ind = xcalloc(1+n, sizeof(int)); + val = xcalloc(1+n, sizeof(double)); + for (i = m; i > pred_m; i--) + { GLPROW *row = mip->row[i]; + IOSROW *r; + const char *name; + r = dmp_get_atom(tree->pool, sizeof(IOSROW)); + name = glp_get_row_name(mip, i); + if (name == NULL) + r->name = NULL; + else + { r->name = dmp_get_atom(tree->pool, strlen(name)+1); + strcpy(r->name, name); + } +#if 1 /* 20/IX-2008 */ + r->origin = row->origin; + r->klass = row->klass; +#endif + r->type = (unsigned char)row->type; + r->lb = row->lb; + r->ub = row->ub; + r->ptr = NULL; + len = glp_get_mat_row(mip, i, ind, val); + for (k = 1; k <= len; k++) + { IOSAIJ *a; + a = dmp_get_atom(tree->pool, sizeof(IOSAIJ)); + a->j = ind[k]; + a->val = val[k]; + a->next = r->ptr; + r->ptr = a; + } + r->rii = row->rii; + r->stat = (unsigned char)row->stat; + r->next = node->r_ptr; + node->r_ptr = r; + } + xfree(ind); + xfree(val); + } + /* remove all rows missing in the root subproblem */ + if (m != root_m) + { int nrs, *num; + nrs = m - root_m; + xassert(nrs > 0); + num = xcalloc(1+nrs, sizeof(int)); + for (i = 1; i <= nrs; i++) num[i] = root_m + i; + glp_del_rows(mip, nrs, num); + xfree(num); + } + m = mip->m; + /* and restore attributes of all rows and columns for the root + subproblem */ + xassert(m == root_m); + for (i = 1; i <= m; i++) + { glp_set_row_bnds(mip, i, tree->root_type[i], + tree->root_lb[i], tree->root_ub[i]); + glp_set_row_stat(mip, i, tree->root_stat[i]); + } + for (j = 1; j <= n; j++) + { glp_set_col_bnds(mip, j, tree->root_type[m+j], + tree->root_lb[m+j], tree->root_ub[m+j]); + glp_set_col_stat(mip, j, tree->root_stat[m+j]); + } +#if 1 + /* remove all edges and cliques missing in the conflict graph + for the root subproblem */ + /* (not implemented yet) */ +#endif + } + /* the current subproblem has been frozen */ + tree->curr = NULL; + return; +} + +/*********************************************************************** +* NAME +* +* ios_clone_node - clone specified subproblem +* +* SYNOPSIS +* +* #include "glpios.h" +* void ios_clone_node(glp_tree *tree, int p, int nnn, int ref[]); +* +* DESCRIPTION +* +* The routine ios_clone_node clones the specified subproblem, whose +* reference number is p, creating its nnn exact copies. Note that the +* specified subproblem must be active and must be in the frozen state +* (i.e. it must not be the current subproblem). +* +* Each clone, an exact copy of the specified subproblem, becomes a new +* active subproblem added to the end of the active list. After cloning +* the specified subproblem becomes inactive. +* +* The reference numbers of clone subproblems are stored to locations +* ref[1], ..., ref[nnn]. */ + +static int get_slot(glp_tree *tree) +{ int p; + /* if no free slots are available, increase the room */ + if (tree->avail == 0) + { int nslots = tree->nslots; + IOSLOT *save = tree->slot; + if (nslots == 0) + tree->nslots = 20; + else + { tree->nslots = nslots + nslots; + xassert(tree->nslots > nslots); + } + tree->slot = xcalloc(1+tree->nslots, sizeof(IOSLOT)); + if (save != NULL) + { memcpy(&tree->slot[1], &save[1], nslots * sizeof(IOSLOT)); + xfree(save); + } + /* push more free slots into the stack */ + for (p = tree->nslots; p > nslots; p--) + { tree->slot[p].node = NULL; + tree->slot[p].next = tree->avail; + tree->avail = p; + } + } + /* pull a free slot from the stack */ + p = tree->avail; + tree->avail = tree->slot[p].next; + xassert(tree->slot[p].node == NULL); + tree->slot[p].next = 0; + return p; +} + +static IOSNPD *new_node(glp_tree *tree, IOSNPD *parent) +{ IOSNPD *node; + int p; + /* pull a free slot for the new node */ + p = get_slot(tree); + /* create descriptor of the new subproblem */ + node = dmp_get_atom(tree->pool, sizeof(IOSNPD)); + tree->slot[p].node = node; + node->p = p; + node->up = parent; + node->level = (parent == NULL ? 0 : parent->level + 1); + node->count = 0; + node->b_ptr = NULL; + node->s_ptr = NULL; + node->r_ptr = NULL; + node->solved = 0; +#if 0 + node->own_nn = node->own_nc = 0; + node->e_ptr = NULL; +#endif +#if 1 /* 04/X-2008 */ + node->lp_obj = (parent == NULL ? (tree->mip->dir == GLP_MIN ? + -DBL_MAX : +DBL_MAX) : parent->lp_obj); +#endif + node->bound = (parent == NULL ? (tree->mip->dir == GLP_MIN ? + -DBL_MAX : +DBL_MAX) : parent->bound); + node->br_var = 0; + node->br_val = 0.0; + node->ii_cnt = 0; + node->ii_sum = 0.0; +#if 1 /* 30/XI-2009 */ + node->changed = 0; +#endif + if (tree->parm->cb_size == 0) + node->data = NULL; + else + { node->data = dmp_get_atom(tree->pool, tree->parm->cb_size); + memset(node->data, 0, tree->parm->cb_size); + } + node->temp = NULL; + node->prev = tree->tail; + node->next = NULL; + /* add the new subproblem to the end of the active list */ + if (tree->head == NULL) + tree->head = node; + else + tree->tail->next = node; + tree->tail = node; + tree->a_cnt++; + tree->n_cnt++; + tree->t_cnt++; + /* increase the number of child subproblems */ + if (parent == NULL) + xassert(p == 1); + else + parent->count++; + return node; +} + +void ios_clone_node(glp_tree *tree, int p, int nnn, int ref[]) +{ IOSNPD *node; + int k; + /* obtain pointer to the subproblem to be cloned */ + xassert(1 <= p && p <= tree->nslots); + node = tree->slot[p].node; + xassert(node != NULL); + /* the specified subproblem must be active */ + xassert(node->count == 0); + /* and must be in the frozen state */ + xassert(tree->curr != node); + /* remove the specified subproblem from the active list, because + it becomes inactive */ + if (node->prev == NULL) + tree->head = node->next; + else + node->prev->next = node->next; + if (node->next == NULL) + tree->tail = node->prev; + else + node->next->prev = node->prev; + node->prev = node->next = NULL; + tree->a_cnt--; + /* create clone subproblems */ + xassert(nnn > 0); + for (k = 1; k <= nnn; k++) + ref[k] = new_node(tree, node)->p; + return; +} + +/*********************************************************************** +* NAME +* +* ios_delete_node - delete specified subproblem +* +* SYNOPSIS +* +* #include "glpios.h" +* void ios_delete_node(glp_tree *tree, int p); +* +* DESCRIPTION +* +* The routine ios_delete_node deletes the specified subproblem, whose +* reference number is p. The subproblem must be active and must be in +* the frozen state (i.e. it must not be the current subproblem). +* +* Note that deletion is performed recursively, i.e. if a subproblem to +* be deleted is the only child of its parent, the parent subproblem is +* also deleted, etc. */ + +void ios_delete_node(glp_tree *tree, int p) +{ IOSNPD *node, *temp; + /* obtain pointer to the subproblem to be deleted */ + xassert(1 <= p && p <= tree->nslots); + node = tree->slot[p].node; + xassert(node != NULL); + /* the specified subproblem must be active */ + xassert(node->count == 0); + /* and must be in the frozen state */ + xassert(tree->curr != node); + /* remove the specified subproblem from the active list, because + it is gone from the tree */ + if (node->prev == NULL) + tree->head = node->next; + else + node->prev->next = node->next; + if (node->next == NULL) + tree->tail = node->prev; + else + node->next->prev = node->prev; + node->prev = node->next = NULL; + tree->a_cnt--; +loop: /* recursive deletion starts here */ + /* delete the bound change list */ + { IOSBND *b; + while (node->b_ptr != NULL) + { b = node->b_ptr; + node->b_ptr = b->next; + dmp_free_atom(tree->pool, b, sizeof(IOSBND)); + } + } + /* delete the status change list */ + { IOSTAT *s; + while (node->s_ptr != NULL) + { s = node->s_ptr; + node->s_ptr = s->next; + dmp_free_atom(tree->pool, s, sizeof(IOSTAT)); + } + } + /* delete the row addition list */ + while (node->r_ptr != NULL) + { IOSROW *r; + r = node->r_ptr; + if (r->name != NULL) + dmp_free_atom(tree->pool, r->name, strlen(r->name)+1); + while (r->ptr != NULL) + { IOSAIJ *a; + a = r->ptr; + r->ptr = a->next; + dmp_free_atom(tree->pool, a, sizeof(IOSAIJ)); + } + node->r_ptr = r->next; + dmp_free_atom(tree->pool, r, sizeof(IOSROW)); + } +#if 0 + /* delete the edge addition list */ + /* delete the clique addition list */ + /* (not implemented yet) */ + xassert(node->own_nn == 0); + xassert(node->own_nc == 0); + xassert(node->e_ptr == NULL); +#endif + /* free application-specific data */ + if (tree->parm->cb_size == 0) + xassert(node->data == NULL); + else + dmp_free_atom(tree->pool, node->data, tree->parm->cb_size); + /* free the corresponding node slot */ + p = node->p; + xassert(tree->slot[p].node == node); + tree->slot[p].node = NULL; + tree->slot[p].next = tree->avail; + tree->avail = p; + /* save pointer to the parent subproblem */ + temp = node->up; + /* delete the subproblem descriptor */ + dmp_free_atom(tree->pool, node, sizeof(IOSNPD)); + tree->n_cnt--; + /* take pointer to the parent subproblem */ + node = temp; + if (node != NULL) + { /* the parent subproblem exists; decrease the number of its + child subproblems */ + xassert(node->count > 0); + node->count--; + /* if now the parent subproblem has no childs, it also must be + deleted */ + if (node->count == 0) goto loop; + } + return; +} + +/*********************************************************************** +* NAME +* +* ios_delete_tree - delete branch-and-bound tree +* +* SYNOPSIS +* +* #include "glpios.h" +* void ios_delete_tree(glp_tree *tree); +* +* DESCRIPTION +* +* The routine ios_delete_tree deletes the branch-and-bound tree, which +* the parameter tree points to, and frees all the memory allocated to +* this program object. +* +* On exit components of the problem object are restored to correspond +* to the original MIP passed to the routine ios_create_tree. */ + +void ios_delete_tree(glp_tree *tree) +{ glp_prob *mip = tree->mip; + int i, j; + int m = mip->m; + int n = mip->n; + xassert(mip->tree == tree); + /* remove all additional rows */ + if (m != tree->orig_m) + { int nrs, *num; + nrs = m - tree->orig_m; + xassert(nrs > 0); + num = xcalloc(1+nrs, sizeof(int)); + for (i = 1; i <= nrs; i++) num[i] = tree->orig_m + i; + glp_del_rows(mip, nrs, num); + xfree(num); + } + m = tree->orig_m; + /* restore original attributes of rows and columns */ + xassert(m == tree->orig_m); + xassert(n == tree->n); + for (i = 1; i <= m; i++) + { glp_set_row_bnds(mip, i, tree->orig_type[i], + tree->orig_lb[i], tree->orig_ub[i]); + glp_set_row_stat(mip, i, tree->orig_stat[i]); + mip->row[i]->prim = tree->orig_prim[i]; + mip->row[i]->dual = tree->orig_dual[i]; + } + for (j = 1; j <= n; j++) + { glp_set_col_bnds(mip, j, tree->orig_type[m+j], + tree->orig_lb[m+j], tree->orig_ub[m+j]); + glp_set_col_stat(mip, j, tree->orig_stat[m+j]); + mip->col[j]->prim = tree->orig_prim[m+j]; + mip->col[j]->dual = tree->orig_dual[m+j]; + } + mip->pbs_stat = mip->dbs_stat = GLP_FEAS; + mip->obj_val = tree->orig_obj; + /* delete the branch-and-bound tree */ + xassert(tree->local != NULL); + ios_delete_pool(tree, tree->local); + dmp_delete_pool(tree->pool); + xfree(tree->orig_type); + xfree(tree->orig_lb); + xfree(tree->orig_ub); + xfree(tree->orig_stat); + xfree(tree->orig_prim); + xfree(tree->orig_dual); + xfree(tree->slot); + if (tree->root_type != NULL) xfree(tree->root_type); + if (tree->root_lb != NULL) xfree(tree->root_lb); + if (tree->root_ub != NULL) xfree(tree->root_ub); + if (tree->root_stat != NULL) xfree(tree->root_stat); + xfree(tree->non_int); +#if 0 + xfree(tree->n_ref); + xfree(tree->c_ref); + xfree(tree->j_ref); +#endif + if (tree->pcost != NULL) ios_pcost_free(tree); + xfree(tree->iwrk); + xfree(tree->dwrk); +#if 0 + scg_delete_graph(tree->g); +#endif + if (tree->pred_type != NULL) xfree(tree->pred_type); + if (tree->pred_lb != NULL) xfree(tree->pred_lb); + if (tree->pred_ub != NULL) xfree(tree->pred_ub); + if (tree->pred_stat != NULL) xfree(tree->pred_stat); +#if 0 + xassert(tree->cut_gen == NULL); +#endif + xassert(tree->mir_gen == NULL); + xassert(tree->clq_gen == NULL); + xfree(tree); + mip->tree = NULL; + return; +} + +/*********************************************************************** +* NAME +* +* ios_eval_degrad - estimate obj. degrad. for down- and up-branches +* +* SYNOPSIS +* +* #include "glpios.h" +* void ios_eval_degrad(glp_tree *tree, int j, double *dn, double *up); +* +* DESCRIPTION +* +* Given optimal basis to LP relaxation of the current subproblem the +* routine ios_eval_degrad performs the dual ratio test to compute the +* objective values in the adjacent basis for down- and up-branches, +* which are stored in locations *dn and *up, assuming that x[j] is a +* variable chosen to branch upon. */ + +void ios_eval_degrad(glp_tree *tree, int j, double *dn, double *up) +{ glp_prob *mip = tree->mip; + int m = mip->m, n = mip->n; + int len, kase, k, t, stat; + double alfa, beta, gamma, delta, dz; + int *ind = tree->iwrk; + double *val = tree->dwrk; + /* current basis must be optimal */ + xassert(glp_get_status(mip) == GLP_OPT); + /* basis factorization must exist */ + xassert(glp_bf_exists(mip)); + /* obtain (fractional) value of x[j] in optimal basic solution + to LP relaxation of the current subproblem */ + xassert(1 <= j && j <= n); + beta = mip->col[j]->prim; + /* since the value of x[j] is fractional, it is basic; compute + corresponding row of the simplex table */ + len = lpx_eval_tab_row(mip, m+j, ind, val); + /* kase < 0 means down-branch; kase > 0 means up-branch */ + for (kase = -1; kase <= +1; kase += 2) + { /* for down-branch we introduce new upper bound floor(beta) + for x[j]; similarly, for up-branch we introduce new lower + bound ceil(beta) for x[j]; in the current basis this new + upper/lower bound is violated, so in the adjacent basis + x[j] will leave the basis and go to its new upper/lower + bound; we need to know which non-basic variable x[k] should + enter the basis to keep dual feasibility */ +#if 0 /* 23/XI-2009 */ + k = lpx_dual_ratio_test(mip, len, ind, val, kase, 1e-7); +#else + k = lpx_dual_ratio_test(mip, len, ind, val, kase, 1e-9); +#endif + /* if no variable has been chosen, current basis being primal + infeasible due to the new upper/lower bound of x[j] is dual + unbounded, therefore, LP relaxation to corresponding branch + has no primal feasible solution */ + if (k == 0) + { if (mip->dir == GLP_MIN) + { if (kase < 0) + *dn = +DBL_MAX; + else + *up = +DBL_MAX; + } + else if (mip->dir == GLP_MAX) + { if (kase < 0) + *dn = -DBL_MAX; + else + *up = -DBL_MAX; + } + else + xassert(mip != mip); + continue; + } + xassert(1 <= k && k <= m+n); + /* row of the simplex table corresponding to specified basic + variable x[j] is the following: + x[j] = ... + alfa * x[k] + ... ; + we need to know influence coefficient, alfa, at non-basic + variable x[k] chosen with the dual ratio test */ + for (t = 1; t <= len; t++) + if (ind[t] == k) break; + xassert(1 <= t && t <= len); + alfa = val[t]; + /* determine status and reduced cost of variable x[k] */ + if (k <= m) + { stat = mip->row[k]->stat; + gamma = mip->row[k]->dual; + } + else + { stat = mip->col[k-m]->stat; + gamma = mip->col[k-m]->dual; + } + /* x[k] cannot be basic or fixed non-basic */ + xassert(stat == GLP_NL || stat == GLP_NU || stat == GLP_NF); + /* if the current basis is dual degenerative, some reduced + costs, which are close to zero, may have wrong sign due to + round-off errors, so correct the sign of gamma */ + if (mip->dir == GLP_MIN) + { if (stat == GLP_NL && gamma < 0.0 || + stat == GLP_NU && gamma > 0.0 || + stat == GLP_NF) gamma = 0.0; + } + else if (mip->dir == GLP_MAX) + { if (stat == GLP_NL && gamma > 0.0 || + stat == GLP_NU && gamma < 0.0 || + stat == GLP_NF) gamma = 0.0; + } + else + xassert(mip != mip); + /* determine the change of x[j] in the adjacent basis: + delta x[j] = new x[j] - old x[j] */ + delta = (kase < 0 ? floor(beta) : ceil(beta)) - beta; + /* compute the change of x[k] in the adjacent basis: + delta x[k] = new x[k] - old x[k] = delta x[j] / alfa */ + delta /= alfa; + /* compute the change of the objective in the adjacent basis: + delta z = new z - old z = gamma * delta x[k] */ + dz = gamma * delta; + if (mip->dir == GLP_MIN) + xassert(dz >= 0.0); + else if (mip->dir == GLP_MAX) + xassert(dz <= 0.0); + else + xassert(mip != mip); + /* compute the new objective value in the adjacent basis: + new z = old z + delta z */ + if (kase < 0) + *dn = mip->obj_val + dz; + else + *up = mip->obj_val + dz; + } + /*xprintf("obj = %g; dn = %g; up = %g\n", + mip->obj_val, *dn, *up);*/ + return; +} + +/*********************************************************************** +* NAME +* +* ios_round_bound - improve local bound by rounding +* +* SYNOPSIS +* +* #include "glpios.h" +* double ios_round_bound(glp_tree *tree, double bound); +* +* RETURNS +* +* For the given local bound for any integer feasible solution to the +* current subproblem the routine ios_round_bound returns an improved +* local bound for the same integer feasible solution. +* +* BACKGROUND +* +* Let the current subproblem has the following objective function: +* +* z = sum c[j] * x[j] + s >= b, (1) +* j in J +* +* where J = {j: c[j] is non-zero and integer, x[j] is integer}, s is +* the sum of terms corresponding to fixed variables, b is an initial +* local bound (minimization). +* +* From (1) it follows that: +* +* d * sum (c[j] / d) * x[j] + s >= b, (2) +* j in J +* +* or, equivalently, +* +* sum (c[j] / d) * x[j] >= (b - s) / d = h, (3) +* j in J +* +* where d = gcd(c[j]). Since the left-hand side of (3) is integer, +* h = (b - s) / d can be rounded up to the nearest integer: +* +* h' = ceil(h) = (b' - s) / d, (4) +* +* that gives an rounded, improved local bound: +* +* b' = d * h' + s. (5) +* +* In case of maximization '>=' in (1) should be replaced by '<=' that +* leads to the following formula: +* +* h' = floor(h) = (b' - s) / d, (6) +* +* which should used in the same way as (4). +* +* NOTE: If b is a valid local bound for a child of the current +* subproblem, b' is also valid for that child subproblem. */ + +double ios_round_bound(glp_tree *tree, double bound) +{ glp_prob *mip = tree->mip; + int n = mip->n; + int d, j, nn, *c = tree->iwrk; + double s, h; + /* determine c[j] and compute s */ + nn = 0, s = mip->c0, d = 0; + for (j = 1; j <= n; j++) + { GLPCOL *col = mip->col[j]; + if (col->coef == 0.0) continue; + if (col->type == GLP_FX) + { /* fixed variable */ + s += col->coef * col->prim; + } + else + { /* non-fixed variable */ + if (col->kind != GLP_IV) goto skip; + if (col->coef != floor(col->coef)) goto skip; + if (fabs(col->coef) <= (double)INT_MAX) + c[++nn] = (int)fabs(col->coef); + else + d = 1; + } + } + /* compute d = gcd(c[1],...c[nn]) */ + if (d == 0) + { if (nn == 0) goto skip; + d = gcdn(nn, c); + } + xassert(d > 0); + /* compute new local bound */ + if (mip->dir == GLP_MIN) + { if (bound != +DBL_MAX) + { h = (bound - s) / (double)d; + if (h >= floor(h) + 0.001) + { /* round up */ + h = ceil(h); + /*xprintf("d = %d; old = %g; ", d, bound);*/ + bound = (double)d * h + s; + /*xprintf("new = %g\n", bound);*/ + } + } + } + else if (mip->dir == GLP_MAX) + { if (bound != -DBL_MAX) + { h = (bound - s) / (double)d; + if (h <= ceil(h) - 0.001) + { /* round down */ + h = floor(h); + bound = (double)d * h + s; + } + } + } + else + xassert(mip != mip); +skip: return bound; +} + +/*********************************************************************** +* NAME +* +* ios_is_hopeful - check if subproblem is hopeful +* +* SYNOPSIS +* +* #include "glpios.h" +* int ios_is_hopeful(glp_tree *tree, double bound); +* +* DESCRIPTION +* +* Given the local bound of a subproblem the routine ios_is_hopeful +* checks if the subproblem can have an integer optimal solution which +* is better than the best one currently known. +* +* RETURNS +* +* If the subproblem can have a better integer optimal solution, the +* routine returns non-zero; otherwise, if the corresponding branch can +* be pruned, the routine returns zero. */ + +int ios_is_hopeful(glp_tree *tree, double bound) +{ glp_prob *mip = tree->mip; + int ret = 1; + double eps; + if (mip->mip_stat == GLP_FEAS) + { eps = tree->parm->tol_obj * (1.0 + fabs(mip->mip_obj)); + switch (mip->dir) + { case GLP_MIN: + if (bound >= mip->mip_obj - eps) ret = 0; + break; + case GLP_MAX: + if (bound <= mip->mip_obj + eps) ret = 0; + break; + default: + xassert(mip != mip); + } + } + else + { switch (mip->dir) + { case GLP_MIN: + if (bound == +DBL_MAX) ret = 0; + break; + case GLP_MAX: + if (bound == -DBL_MAX) ret = 0; + break; + default: + xassert(mip != mip); + } + } + return ret; +} + +/*********************************************************************** +* NAME +* +* ios_best_node - find active node with best local bound +* +* SYNOPSIS +* +* #include "glpios.h" +* int ios_best_node(glp_tree *tree); +* +* DESCRIPTION +* +* The routine ios_best_node finds an active node whose local bound is +* best among other active nodes. +* +* It is understood that the integer optimal solution of the original +* mip problem cannot be better than the best bound, so the best bound +* is an lower (minimization) or upper (maximization) global bound for +* the original problem. +* +* RETURNS +* +* The routine ios_best_node returns the subproblem reference number +* for the best node. However, if the tree is empty, it returns zero. */ + +int ios_best_node(glp_tree *tree) +{ IOSNPD *node, *best = NULL; + switch (tree->mip->dir) + { case GLP_MIN: + /* minimization */ + for (node = tree->head; node != NULL; node = node->next) + if (best == NULL || best->bound > node->bound) + best = node; + break; + case GLP_MAX: + /* maximization */ + for (node = tree->head; node != NULL; node = node->next) + if (best == NULL || best->bound < node->bound) + best = node; + break; + default: + xassert(tree != tree); + } + return best == NULL ? 0 : best->p; +} + +/*********************************************************************** +* NAME +* +* ios_relative_gap - compute relative mip gap +* +* SYNOPSIS +* +* #include "glpios.h" +* double ios_relative_gap(glp_tree *tree); +* +* DESCRIPTION +* +* The routine ios_relative_gap computes the relative mip gap using the +* formula: +* +* gap = |best_mip - best_bnd| / (|best_mip| + DBL_EPSILON), +* +* where best_mip is the best integer feasible solution found so far, +* best_bnd is the best (global) bound. If no integer feasible solution +* has been found yet, rel_gap is set to DBL_MAX. +* +* RETURNS +* +* The routine ios_relative_gap returns the relative mip gap. */ + +double ios_relative_gap(glp_tree *tree) +{ glp_prob *mip = tree->mip; + int p; + double best_mip, best_bnd, gap; + if (mip->mip_stat == GLP_FEAS) + { best_mip = mip->mip_obj; + p = ios_best_node(tree); + if (p == 0) + { /* the tree is empty */ + gap = 0.0; + } + else + { best_bnd = tree->slot[p].node->bound; + gap = fabs(best_mip - best_bnd) / (fabs(best_mip) + + DBL_EPSILON); + } + } + else + { /* no integer feasible solution has been found yet */ + gap = DBL_MAX; + } + return gap; +} + +/*********************************************************************** +* NAME +* +* ios_solve_node - solve LP relaxation of current subproblem +* +* SYNOPSIS +* +* #include "glpios.h" +* int ios_solve_node(glp_tree *tree); +* +* DESCRIPTION +* +* The routine ios_solve_node re-optimizes LP relaxation of the current +* subproblem using the dual simplex method. +* +* RETURNS +* +* The routine returns the code which is reported by glp_simplex. */ + +int ios_solve_node(glp_tree *tree) +{ glp_prob *mip = tree->mip; + glp_smcp parm; + int ret; + /* the current subproblem must exist */ + xassert(tree->curr != NULL); + /* set some control parameters */ + glp_init_smcp(&parm); + switch (tree->parm->msg_lev) + { case GLP_MSG_OFF: + parm.msg_lev = GLP_MSG_OFF; break; + case GLP_MSG_ERR: + parm.msg_lev = GLP_MSG_ERR; break; + case GLP_MSG_ON: + case GLP_MSG_ALL: + parm.msg_lev = GLP_MSG_ON; break; + case GLP_MSG_DBG: + parm.msg_lev = GLP_MSG_ALL; break; + default: + xassert(tree != tree); + } + parm.meth = GLP_DUALP; + if (tree->parm->msg_lev < GLP_MSG_DBG) + parm.out_dly = tree->parm->out_dly; + else + parm.out_dly = 0; + /* if the incumbent objective value is already known, use it to + prematurely terminate the dual simplex search */ + if (mip->mip_stat == GLP_FEAS) + { switch (tree->mip->dir) + { case GLP_MIN: + parm.obj_ul = mip->mip_obj; + break; + case GLP_MAX: + parm.obj_ll = mip->mip_obj; + break; + default: + xassert(mip != mip); + } + } + /* try to solve/re-optimize the LP relaxation */ + ret = glp_simplex(mip, &parm); + tree->curr->solved++; +#if 0 + xprintf("ret = %d; status = %d; pbs = %d; dbs = %d; some = %d\n", + ret, glp_get_status(mip), mip->pbs_stat, mip->dbs_stat, + mip->some); + lpx_print_sol(mip, "sol"); +#endif + return ret; +} + +/**********************************************************************/ + +IOSPOOL *ios_create_pool(glp_tree *tree) +{ /* create cut pool */ + IOSPOOL *pool; +#if 0 + pool = dmp_get_atom(tree->pool, sizeof(IOSPOOL)); +#else + xassert(tree == tree); + pool = xmalloc(sizeof(IOSPOOL)); +#endif + pool->size = 0; + pool->head = pool->tail = NULL; + pool->ord = 0, pool->curr = NULL; + return pool; +} + +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 */ + IOSCUT *cut; + IOSAIJ *aij; + int k; + xassert(pool != NULL); + cut = dmp_get_atom(tree->pool, sizeof(IOSCUT)); + if (name == NULL || name[0] == '\0') + cut->name = NULL; + else + { for (k = 0; name[k] != '\0'; k++) + { if (k == 256) + xerror("glp_ios_add_row: cut name too long\n"); + if (iscntrl((unsigned char)name[k])) + xerror("glp_ios_add_row: cut name contains invalid chara" + "cter(s)\n"); + } + cut->name = dmp_get_atom(tree->pool, strlen(name)+1); + strcpy(cut->name, name); + } + if (!(0 <= klass && klass <= 255)) + xerror("glp_ios_add_row: klass = %d; invalid cut class\n", + klass); + cut->klass = (unsigned char)klass; + if (flags != 0) + xerror("glp_ios_add_row: flags = %d; invalid cut flags\n", + flags); + cut->ptr = NULL; + if (!(0 <= len && len <= tree->n)) + xerror("glp_ios_add_row: len = %d; invalid cut length\n", + len); + for (k = 1; k <= len; k++) + { aij = dmp_get_atom(tree->pool, sizeof(IOSAIJ)); + if (!(1 <= ind[k] && ind[k] <= tree->n)) + xerror("glp_ios_add_row: ind[%d] = %d; column index out of " + "range\n", k, ind[k]); + aij->j = ind[k]; + aij->val = val[k]; + aij->next = cut->ptr; + cut->ptr = aij; + } + if (!(type == GLP_LO || type == GLP_UP || type == GLP_FX)) + xerror("glp_ios_add_row: type = %d; invalid cut type\n", + type); + cut->type = (unsigned char)type; + cut->rhs = rhs; + cut->prev = pool->tail; + cut->next = NULL; + if (cut->prev == NULL) + pool->head = cut; + else + cut->prev->next = cut; + pool->tail = cut; + pool->size++; + return pool->size; +} + +IOSCUT *ios_find_row(IOSPOOL *pool, int i) +{ /* find row (constraint) in the cut pool */ + /* (smart linear search) */ + xassert(pool != NULL); + xassert(1 <= i && i <= pool->size); + if (pool->ord == 0) + { xassert(pool->curr == NULL); + pool->ord = 1; + pool->curr = pool->head; + } + xassert(pool->curr != NULL); + if (i < pool->ord) + { if (i < pool->ord - i) + { pool->ord = 1; + pool->curr = pool->head; + while (pool->ord != i) + { pool->ord++; + xassert(pool->curr != NULL); + pool->curr = pool->curr->next; + } + } + else + { while (pool->ord != i) + { pool->ord--; + xassert(pool->curr != NULL); + pool->curr = pool->curr->prev; + } + } + } + else if (i > pool->ord) + { if (i - pool->ord < pool->size - i) + { while (pool->ord != i) + { pool->ord++; + xassert(pool->curr != NULL); + pool->curr = pool->curr->next; + } + } + else + { pool->ord = pool->size; + pool->curr = pool->tail; + while (pool->ord != i) + { pool->ord--; + xassert(pool->curr != NULL); + pool->curr = pool->curr->prev; + } + } + } + xassert(pool->ord == i); + xassert(pool->curr != NULL); + return pool->curr; +} + +void ios_del_row(glp_tree *tree, IOSPOOL *pool, int i) +{ /* remove row (constraint) from the cut pool */ + IOSCUT *cut; + IOSAIJ *aij; + xassert(pool != NULL); + if (!(1 <= i && i <= pool->size)) + xerror("glp_ios_del_row: i = %d; cut number out of range\n", + i); + cut = ios_find_row(pool, i); + xassert(pool->curr == cut); + if (cut->next != NULL) + pool->curr = cut->next; + else if (cut->prev != NULL) + pool->ord--, pool->curr = cut->prev; + else + pool->ord = 0, pool->curr = NULL; + if (cut->name != NULL) + dmp_free_atom(tree->pool, cut->name, strlen(cut->name)+1); + if (cut->prev == NULL) + { xassert(pool->head == cut); + pool->head = cut->next; + } + else + { xassert(cut->prev->next == cut); + cut->prev->next = cut->next; + } + if (cut->next == NULL) + { xassert(pool->tail == cut); + pool->tail = cut->prev; + } + else + { xassert(cut->next->prev == cut); + cut->next->prev = cut->prev; + } + while (cut->ptr != NULL) + { aij = cut->ptr; + cut->ptr = aij->next; + dmp_free_atom(tree->pool, aij, sizeof(IOSAIJ)); + } + dmp_free_atom(tree->pool, cut, sizeof(IOSCUT)); + pool->size--; + return; +} + +void ios_clear_pool(glp_tree *tree, IOSPOOL *pool) +{ /* remove all rows (constraints) from the cut pool */ + xassert(pool != NULL); + while (pool->head != NULL) + { IOSCUT *cut = pool->head; + pool->head = cut->next; + if (cut->name != NULL) + dmp_free_atom(tree->pool, cut->name, strlen(cut->name)+1); + while (cut->ptr != NULL) + { IOSAIJ *aij = cut->ptr; + cut->ptr = aij->next; + dmp_free_atom(tree->pool, aij, sizeof(IOSAIJ)); + } + dmp_free_atom(tree->pool, cut, sizeof(IOSCUT)); + } + pool->size = 0; + pool->head = pool->tail = NULL; + pool->ord = 0, pool->curr = NULL; + return; +} + +void ios_delete_pool(glp_tree *tree, IOSPOOL *pool) +{ /* delete cut pool */ + xassert(pool != NULL); + ios_clear_pool(tree, pool); + xfree(pool); + return; +} + +/**********************************************************************/ + +#if 0 +static int refer_to_node(glp_tree *tree, int j) +{ /* determine node number corresponding to binary variable x[j] or + its complement */ + glp_prob *mip = tree->mip; + int n = mip->n; + int *ref; + if (j > 0) + ref = tree->n_ref; + else + ref = tree->c_ref, j = - j; + xassert(1 <= j && j <= n); + if (ref[j] == 0) + { /* new node is needed */ + SCG *g = tree->g; + int n_max = g->n_max; + ref[j] = scg_add_nodes(g, 1); + if (g->n_max > n_max) + { int *save = tree->j_ref; + tree->j_ref = xcalloc(1+g->n_max, sizeof(int)); + memcpy(&tree->j_ref[1], &save[1], g->n * sizeof(int)); + xfree(save); + } + xassert(ref[j] == g->n); + tree->j_ref[ref[j]] = j; + xassert(tree->curr != NULL); + if (tree->curr->level > 0) tree->curr->own_nn++; + } + return ref[j]; +} +#endif + +#if 0 +void ios_add_edge(glp_tree *tree, int j1, int j2) +{ /* add new edge to the conflict graph */ + glp_prob *mip = tree->mip; + int n = mip->n; + SCGRIB *e; + int first, i1, i2; + xassert(-n <= j1 && j1 <= +n && j1 != 0); + xassert(-n <= j2 && j2 <= +n && j2 != 0); + xassert(j1 != j2); + /* determine number of the first node, which was added for the + current subproblem */ + xassert(tree->curr != NULL); + first = tree->g->n - tree->curr->own_nn + 1; + /* determine node numbers for both endpoints */ + i1 = refer_to_node(tree, j1); + i2 = refer_to_node(tree, j2); + /* add edge (i1,i2) to the conflict graph */ + e = scg_add_edge(tree->g, i1, i2); + /* if the current subproblem is not the root and both endpoints + were created on some previous levels, save the edge */ + if (tree->curr->level > 0 && i1 < first && i2 < first) + { IOSRIB *rib; + rib = dmp_get_atom(tree->pool, sizeof(IOSRIB)); + rib->j1 = j1; + rib->j2 = j2; + rib->e = e; + rib->next = tree->curr->e_ptr; + tree->curr->e_ptr = rib; + } + return; +} +#endif + +/* eof */