1 files changed, 106 insertions, 0 deletions
diff --git a/src/misc/espresso/gimpel.c b/src/misc/espresso/gimpel.c
new file mode 100644
index 00000000..648bb64a
--- /dev/null
+++ b/src/misc/espresso/gimpel.c
@@ -0,0 +1,106 @@
+/*
+ * Revision Control Information
+ *
+ * $Source$
+ * $Author$
+ * $Revision$
+ * $Date$
+ *
+ */
+#include "mincov_int.h"
+
+
+/*
+ *  check for:
+ *
+ *        c1    c2    rest
+ *        --      --      ---
+ *         1     1    0 0 0 0        <-- primary row
+ *         1     0    S1        <-- secondary row
+ *         0       1    T1
+ *         0       1    T2
+ *         0       1    Tn
+ *         0       0      R
+ */
+
+int
+gimpel_reduce(A, select, weight, lb, bound, depth, stats, best)
+sm_matrix *A;
+solution_t *select;
+int *weight;
+int lb;
+int bound;
+int depth;
+stats_t *stats;
+solution_t **best;
+{
+    register sm_row *prow, *save_sec;
+    register sm_col *c1, *c2;
+    register sm_element *p, *p1;
+    int c1_col_num, c2_col_num, primary_row_num, secondary_row_num;
+    int reduce_it; 
+
+    reduce_it = 0;
+    for(prow = A->first_row; prow != 0; prow = prow->next_row) {
+    if (prow->length == 2) {
+        c1 = sm_get_col(A, prow->first_col->col_num);
+        c2 = sm_get_col(A, prow->last_col->col_num);
+        if (c1->length == 2) {
+        reduce_it = 1;
+        } else if (c2->length == 2) {
+        c1 = sm_get_col(A, prow->last_col->col_num);
+        c2 = sm_get_col(A, prow->first_col->col_num);
+        reduce_it = 1;
+        }
+        if (reduce_it) {
+        primary_row_num = prow->row_num;
+        secondary_row_num = c1->first_row->row_num;
+        if (secondary_row_num == primary_row_num) {
+            secondary_row_num = c1->last_row->row_num;
+        }
+        break;
+        }
+    }
+    }
+
+    if (reduce_it) {
+    c1_col_num = c1->col_num;
+    c2_col_num = c2->col_num;
+    save_sec = sm_row_dup(sm_get_row(A, secondary_row_num));
+    sm_row_remove(save_sec, c1_col_num);
+
+    for(p = c2->first_row; p != 0; p = p->next_row) {
+        if (p->row_num != primary_row_num) {
+        /* merge rows S1 and T */
+        for(p1 = save_sec->first_col; p1 != 0; p1 = p1->next_col) {
+            (void) sm_insert(A, p->row_num, p1->col_num);
+        }
+        }
+    }
+
+    sm_delcol(A, c1_col_num);
+    sm_delcol(A, c2_col_num);
+    sm_delrow(A, primary_row_num);
+    sm_delrow(A, secondary_row_num);
+
+    stats->gimpel_count++;
+    stats->gimpel++;
+    *best = sm_mincov(A, select, weight, lb-1, bound-1, depth, stats);
+    stats->gimpel--;
+
+    if (*best != NIL(solution_t)) {
+        /* is secondary row covered ? */
+        if (sm_row_intersects(save_sec, (*best)->row)) {
+        /* yes, actually select c2 */
+        solution_add(*best, weight, c2_col_num);
+        } else {
+        solution_add(*best, weight, c1_col_num);
+        }
+    }
+
+    sm_row_free(save_sec);
+    return 1;
+    } else {
+    return 0;
+    }
+}