double MtxLP::getRowLB(string name)const{
return get_row_lb(nrow(name));
}
void *lpx_create_cog(LPX *lp)
{ struct COG *cog = NULL;
int m, n, nb, i, j, p, q, len, *ind, *vert, *orig;
double L, U, lf_min, lf_max, *val;
xprintf("Creating the conflict graph...\n");
m = lpx_get_num_rows(lp);
n = lpx_get_num_cols(lp);
/* determine which binary variables should be included in the
conflict graph */
nb = 0;
vert = xcalloc(1+n, sizeof(int));
for (j = 1; j <= n; j++) vert[j] = 0;
orig = xcalloc(1+n, sizeof(int));
ind = xcalloc(1+n, sizeof(int));
val = xcalloc(1+n, sizeof(double));
for (i = 1; i <= m; i++)
{ L = get_row_lb(lp, i);
U = get_row_ub(lp, i);
if (L == -DBL_MAX && U == +DBL_MAX) continue;
len = lpx_get_mat_row(lp, i, ind, val);
if (len > MAX_ROW_LEN) continue;
lf_min = eval_lf_min(lp, len, ind, val);
lf_max = eval_lf_max(lp, len, ind, val);
for (p = 1; p <= len; p++)
{ if (!is_binary(lp, ind[p])) continue;
for (q = p+1; q <= len; q++)
{ if (!is_binary(lp, ind[q])) continue;
if (probing(len, val, L, U, lf_min, lf_max, p, 0, q) ||
probing(len, val, L, U, lf_min, lf_max, p, 1, q))
{ /* there is a logical relation */
/* include the first variable in the graph */
j = ind[p];
if (vert[j] == 0) nb++, vert[j] = nb, orig[nb] = j;
/* incude the second variable in the graph */
j = ind[q];
if (vert[j] == 0) nb++, vert[j] = nb, orig[nb] = j;
}
}
}
}
/* if the graph is either empty or has too many vertices, do not
create it */
if (nb == 0 || nb > MAX_NB)
{ xprintf("The conflict graph is either empty or too big\n");
xfree(vert);
xfree(orig);
goto done;
}
/* create the conflict graph */
cog = xmalloc(sizeof(struct COG));
cog->n = n;
cog->nb = nb;
cog->ne = 0;
cog->vert = vert;
cog->orig = orig;
len = nb + nb; /* number of vertices */
len = (len * (len - 1)) / 2; /* number of entries in triangle */
len = (len + (CHAR_BIT - 1)) / CHAR_BIT; /* bytes needed */
cog->a = xmalloc(len);
memset(cog->a, 0, len);
for (j = 1; j <= nb; j++)
{ /* add edge between variable and its complement */
lpx_add_cog_edge(cog, +orig[j], -orig[j]);
}
for (i = 1; i <= m; i++)
{ L = get_row_lb(lp, i);
U = get_row_ub(lp, i);
if (L == -DBL_MAX && U == +DBL_MAX) continue;
len = lpx_get_mat_row(lp, i, ind, val);
if (len > MAX_ROW_LEN) continue;
lf_min = eval_lf_min(lp, len, ind, val);
lf_max = eval_lf_max(lp, len, ind, val);
for (p = 1; p <= len; p++)
{ if (!is_binary(lp, ind[p])) continue;
for (q = p+1; q <= len; q++)
{ if (!is_binary(lp, ind[q])) continue;
/* set x[p] to 0 and examine x[q] */
switch (probing(len, val, L, U, lf_min, lf_max, p, 0, q))
{ case 0:
/* no logical relation */
break;
case 1:
/* x[p] = 0 implies x[q] = 0 */
lpx_add_cog_edge(cog, -ind[p], +ind[q]);
break;
case 2:
/* x[p] = 0 implies x[q] = 1 */
lpx_add_cog_edge(cog, -ind[p], -ind[q]);
break;
default:
xassert(lp != lp);
}
/* set x[p] to 1 and examine x[q] */
switch (probing(len, val, L, U, lf_min, lf_max, p, 1, q))
{ case 0:
/* no logical relation */
break;
case 1:
/* x[p] = 1 implies x[q] = 0 */
lpx_add_cog_edge(cog, +ind[p], +ind[q]);
break;
case 2:
/* x[p] = 1 implies x[q] = 1 */
lpx_add_cog_edge(cog, +ind[p], -ind[q]);
break;
default:
xassert(lp != lp);
}
}
}
}
xprintf("The conflict graph has 2*%d vertices and %d edges\n",
cog->nb, cog->ne);
done: xfree(ind);
xfree(val);
return cog;
}
