Version abc60220

1 files changed, 675 insertions, 0 deletions

diff --git a/src/misc/espresso/pair.c b/src/misc/espresso/pair.c
new file mode 100644
index 00000000..a8077176
--- /dev/null
+++ b/src/misc/espresso/pair.c
@@ -0,0 +1,675 @@
+/*
+ * Revision Control Information
+ *
+ * $Source$
+ * $Author$
+ * $Revision$
+ * $Date$
+ *
+ */
+#include "espresso.h"
+
+void set_pair(PLA)
+pPLA PLA;
+{
+    set_pair1(PLA, TRUE);
+}
+
+void set_pair1(PLA, adjust_labels)
+pPLA PLA;
+bool adjust_labels;
+{
+    int i, var, *paired, newvar;
+    int old_num_vars, old_num_binary_vars, old_size, old_mv_start;
+    int *new_part_size, new_num_vars, new_num_binary_vars, new_mv_start;
+    ppair pair = PLA->pair;
+    char scratch[1000], **oldlabel, *var1, *var1bar, *var2, *var2bar;
+
+    if (adjust_labels)
+    makeup_labels(PLA);
+
+    /* Check the pair structure for valid entries and see which binary
+    variables are left unpaired
+    */
+    paired = ALLOC(bool, cube.num_binary_vars);
+    for(var = 0; var < cube.num_binary_vars; var++)
+    paired[var] = FALSE;
+    for(i = 0; i < pair->cnt; i++)
+    if ((pair->var1[i] > 0 && pair->var1[i] <= cube.num_binary_vars) &&
+         (pair->var2[i] > 0 && pair->var2[i] <= cube.num_binary_vars)) {
+        paired[pair->var1[i]-1] = TRUE;
+        paired[pair->var2[i]-1] = TRUE;
+    } else
+        fatal("can only pair binary-valued variables");
+
+    PLA->F = delvar(pairvar(PLA->F, pair), paired);
+    PLA->R = delvar(pairvar(PLA->R, pair), paired);
+    PLA->D = delvar(pairvar(PLA->D, pair), paired);
+
+    /* Now painfully adjust the cube size */
+    old_size = cube.size;
+    old_num_vars = cube.num_vars;
+    old_num_binary_vars = cube.num_binary_vars;
+    old_mv_start = cube.first_part[cube.num_binary_vars];
+    /* Create the new cube.part_size vector and setup the cube structure */
+    new_num_binary_vars = 0;
+    for(var = 0; var < old_num_binary_vars; var++)
+    new_num_binary_vars += (paired[var] == FALSE);
+    new_num_vars = new_num_binary_vars + pair->cnt;
+    new_num_vars += old_num_vars - old_num_binary_vars;
+    new_part_size = ALLOC(int, new_num_vars);
+    for(var = 0; var < pair->cnt; var++)
+    new_part_size[new_num_binary_vars + var] = 4;
+    for(var = 0; var < old_num_vars - old_num_binary_vars; var++)
+    new_part_size[new_num_binary_vars + pair->cnt + var] =
+        cube.part_size[old_num_binary_vars + var];
+    setdown_cube();
+    FREE(cube.part_size);
+    cube.num_vars = new_num_vars;
+    cube.num_binary_vars = new_num_binary_vars;
+    cube.part_size = new_part_size;
+    cube_setup();
+
+    /* hack with the labels to get them correct */
+    if (adjust_labels) {
+    oldlabel = PLA->label;
+    PLA->label = ALLOC(char *, cube.size);
+    for(var = 0; var < pair->cnt; var++) {
+        newvar = cube.num_binary_vars*2 + var*4;
+        var1 = oldlabel[ (pair->var1[var]-1) * 2 + 1];
+        var2 = oldlabel[ (pair->var2[var]-1) * 2 + 1];
+        var1bar = oldlabel[ (pair->var1[var]-1) * 2];
+        var2bar = oldlabel[ (pair->var2[var]-1) * 2];
+        (void) sprintf(scratch, "%s+%s", var1bar, var2bar);
+        PLA->label[newvar] = util_strsav(scratch);
+        (void) sprintf(scratch, "%s+%s", var1bar, var2);
+        PLA->label[newvar+1] = util_strsav(scratch);
+        (void) sprintf(scratch, "%s+%s", var1, var2bar);
+        PLA->label[newvar+2] = util_strsav(scratch);
+        (void) sprintf(scratch, "%s+%s", var1, var2);
+        PLA->label[newvar+3] = util_strsav(scratch);
+    }
+    /* Copy the old labels for the unpaired binary vars */
+    i = 0;
+    for(var = 0; var < old_num_binary_vars; var++) {
+        if (paired[var] == FALSE) {
+        PLA->label[2*i] = oldlabel[2*var];
+        PLA->label[2*i+1] = oldlabel[2*var+1];
+        oldlabel[2*var] = oldlabel[2*var+1] = (char *) NULL;
+        i++;
+        }
+    }
+    /* Copy the old labels for the remaining unpaired vars */
+    new_mv_start = cube.num_binary_vars*2 + pair->cnt*4;
+    for(i = old_mv_start; i < old_size; i++) {
+        PLA->label[new_mv_start + i - old_mv_start] = oldlabel[i];
+        oldlabel[i] = (char *) NULL;
+    }
+    /* free remaining entries in oldlabel */
+    for(i = 0; i < old_size; i++)
+        if (oldlabel[i] != (char *) NULL)
+        FREE(oldlabel[i]);
+    FREE(oldlabel);
+    }
+
+    /* the paired variables should not be sparse (cf. mv_reduce/raise_in)*/
+    for(var = 0; var < pair->cnt; var++)
+    cube.sparse[cube.num_binary_vars + var] = 0;
+    FREE(paired);
+}
+
+pcover pairvar(A, pair)
+pcover A;
+ppair pair;
+{
+    register pcube last, p;
+    register int val, p1, p2, b1, b0;
+    int insert_col, pairnum;
+
+    insert_col = cube.first_part[cube.num_vars - 1];
+
+    /* stretch the cover matrix to make room for the paired variables */
+    A = sf_delcol(A, insert_col, -4*pair->cnt);
+
+    /* compute the paired values */
+    foreach_set(A, last, p) {
+    for(pairnum = 0; pairnum < pair->cnt; pairnum++) {
+        p1 = cube.first_part[pair->var1[pairnum] - 1];
+        p2 = cube.first_part[pair->var2[pairnum] - 1];
+        b1 = is_in_set(p, p2+1);
+        b0 = is_in_set(p, p2);
+        val = insert_col + pairnum * 4;
+        if (/* a0 */ is_in_set(p, p1)) {
+        if (b0)
+            set_insert(p, val + 3);
+        if (b1)
+            set_insert(p, val + 2);
+        }
+        if (/* a1 */ is_in_set(p, p1+1)) {
+        if (b0)
+            set_insert(p, val + 1);
+        if (b1)
+            set_insert(p, val);
+        }
+    }
+    }
+    return A;
+}
+
+
+/* delvar -- delete variables from A, minimize the number of column shifts */
+pcover delvar(A, paired)
+pcover A;
+bool paired[];
+{
+    bool run;
+    int first_run, run_length, var, offset = 0;
+
+    run = FALSE; run_length = 0;
+    for(var = 0; var < cube.num_binary_vars; var++)
+    if (paired[var])
+        if (run)
+        run_length += cube.part_size[var];
+        else {
+        run = TRUE;
+        first_run = cube.first_part[var];
+        run_length = cube.part_size[var];
+        }
+    else
+        if (run) {
+        A = sf_delcol(A, first_run-offset, run_length);
+        run = FALSE;
+        offset += run_length;
+        }
+    if (run)
+    A = sf_delcol(A, first_run-offset, run_length);
+    return A;
+}
+
+/*
+    find_optimal_pairing -- find which binary variables should be paired
+    to maximally reduce the number of terms
+
+    This is essentially the technique outlined by T. Sasao in the
+    Trans. on Comp., Oct 1984.  We estimate the cost of pairing each
+    pair individually using 1 of 4 strategies: (1) algebraic division
+    of F by the pair (exactly T. Sasao technique); (2) strong division
+    of F by the paired variables (using REDUCE/EXPAND/ IRREDUNDANT from
+    espresso); (3) full minimization using espresso; (4) exact
+    minimization.  These are in order of both increasing accuracy and
+    increasing difficulty (!)
+
+    Once the n squared pairs have been evaluated, T. Sasao proposes a
+    graph covering of nodes by disjoint edges.  For now, I solve this
+    problem exhaustively (complexity = (n-1)*(n-3)*...*3*1 for n
+    variables when n is even).  Note that solving this problem exactly
+    is the same as evaluating the cost function for all possible
+    pairings.
+
+                   n       pairs
+
+                 1, 2           1
+                 3, 4           3
+                 5, 6          15
+                 7, 8         105
+                 9,10         945
+                11,12      10,395
+                13,14     135,135
+                15,16   2,027,025
+                17,18  34,459,425
+                19,20 654,729,075
+*/
+void find_optimal_pairing(PLA, strategy)
+pPLA PLA;
+int strategy;
+{
+    int i, j, **cost_array;
+
+    cost_array = find_pairing_cost(PLA, strategy);
+
+    if (summary) {
+    printf("    ");
+    for(i = 0; i < cube.num_binary_vars; i++)
+        printf("%3d ", i+1);
+    printf("\n");
+    for(i = 0; i < cube.num_binary_vars; i++) {
+        printf("%3d ", i+1);
+        for(j = 0; j < cube.num_binary_vars; j++)
+        printf("%3d ", cost_array[i][j]);
+        printf("\n");
+    }
+    }
+
+    if (cube.num_binary_vars <= 14) {
+    PLA->pair = pair_best_cost(cost_array);
+    } else {
+    (void) greedy_best_cost(cost_array, &(PLA->pair));
+    }
+    printf("# ");
+    print_pair(PLA->pair);
+    
+    for(i = 0; i < cube.num_binary_vars; i++)
+    FREE(cost_array[i]);
+    FREE(cost_array);
+
+    set_pair(PLA);
+    EXEC_S(PLA->F=espresso(PLA->F,PLA->D,PLA->R),"ESPRESSO  ",PLA->F);
+}
+
+int **find_pairing_cost(PLA, strategy)
+pPLA PLA;
+int strategy;
+{
+    int var1, var2, **cost_array;
+    int i, j, xnum_binary_vars, xnum_vars, *xpart_size, cost;
+    pcover T, Fsave, Dsave, Rsave;
+    pset mask;
+/*    char *s;*/
+
+    /* data is returned in the cost array */
+    cost_array = ALLOC(int *, cube.num_binary_vars);
+    for(i = 0; i < cube.num_binary_vars; i++)
+    cost_array[i] = ALLOC(int, cube.num_binary_vars);
+    for(i = 0; i < cube.num_binary_vars; i++)
+    for(j = 0; j < cube.num_binary_vars; j++)
+        cost_array[i][j] = 0;
+
+    /* Setup the pair structure for pairing variables together */
+    PLA->pair = pair_new(1);
+    PLA->pair->cnt = 1;
+
+    for(var1 = 0; var1 < cube.num_binary_vars-1; var1++) {
+    for(var2 = var1+1; var2 < cube.num_binary_vars; var2++) {
+        /* if anything but simple strategy, perform setup */
+        if (strategy > 0) {
+        /* save the original covers */
+        Fsave = sf_save(PLA->F);
+        Dsave = sf_save(PLA->D);
+        Rsave = sf_save(PLA->R);
+
+        /* save the original cube structure */
+        xnum_binary_vars = cube.num_binary_vars;
+        xnum_vars = cube.num_vars;
+        xpart_size = ALLOC(int, cube.num_vars);
+        for(i = 0; i < cube.num_vars; i++)
+            xpart_size[i] = cube.part_size[i];
+
+        /* pair two variables together */
+        PLA->pair->var1[0] = var1 + 1;
+        PLA->pair->var2[0] = var2 + 1;
+        set_pair1(PLA, /* adjust_labels */ FALSE);
+        }
+
+
+        /* decide how to best estimate worth of this pairing */
+        switch(strategy) {
+        case 3:
+            /*s = "exact minimization";*/
+            PLA->F = minimize_exact(PLA->F, PLA->D, PLA->R, 1);
+            cost = Fsave->count - PLA->F->count;
+            break;
+        case 2:
+            /*s = "full minimization";*/
+            PLA->F = espresso(PLA->F, PLA->D, PLA->R);
+            cost = Fsave->count - PLA->F->count;
+            break;
+        case 1:
+            /*s = "strong division";*/
+            PLA->F = reduce(PLA->F, PLA->D);
+            PLA->F = expand(PLA->F, PLA->R, FALSE);
+            PLA->F = irredundant(PLA->F, PLA->D);
+            cost = Fsave->count - PLA->F->count;
+            break;
+        case 0:
+            /*s = "weak division";*/
+            mask = new_cube();
+            set_or(mask, cube.var_mask[var1], cube.var_mask[var2]);
+            T = dist_merge(sf_save(PLA->F), mask);
+            cost = PLA->F->count - T->count;
+            sf_free(T);
+            set_free(mask);
+        }
+
+        cost_array[var1][var2] = cost;
+
+        if (strategy > 0) {
+        /* restore the original cube structure -- free the new ones */
+        setdown_cube();
+        FREE(cube.part_size);
+        cube.num_binary_vars = xnum_binary_vars;
+        cube.num_vars = xnum_vars;
+        cube.part_size = xpart_size;
+        cube_setup();
+
+        /* restore the original cover(s) -- free the new ones */
+        sf_free(PLA->F);
+        sf_free(PLA->D);
+        sf_free(PLA->R);
+        PLA->F = Fsave;
+        PLA->D = Dsave;
+        PLA->R = Rsave;
+        }
+    }
+    }
+
+    pair_free(PLA->pair);
+    PLA->pair = NULL;
+    return cost_array;
+}
+
+static int best_cost;
+static int **cost_array;
+static ppair best_pair;
+static pset best_phase;
+static pPLA global_PLA;
+static pcover best_F, best_D, best_R;
+static int pair_minim_strategy;
+
+
+print_pair(pair)
+ppair pair;
+{
+    int i;
+
+    printf("pair is");
+    for(i = 0; i < pair->cnt; i++)
+    printf (" (%d %d)", pair->var1[i], pair->var2[i]);
+    printf("\n");
+}
+
+
+int greedy_best_cost(cost_array_local, pair_p)
+int **cost_array_local;
+ppair *pair_p;
+{
+    int i, j, besti, bestj, maxcost, total_cost;
+    pset cand;
+    ppair pair;
+
+    pair = pair_new(cube.num_binary_vars);
+    cand = set_full(cube.num_binary_vars);
+    total_cost = 0;
+
+    while (set_ord(cand) >= 2) {
+    maxcost = -1;
+    for(i = 0; i < cube.num_binary_vars; i++) {
+        if (is_in_set(cand, i)) {
+        for(j = i+1; j < cube.num_binary_vars; j++) {
+            if (is_in_set(cand, j)) {
+            if (cost_array_local[i][j] > maxcost) {
+                maxcost = cost_array_local[i][j];
+                besti = i;
+                bestj = j;
+            }
+            }
+        }
+        }
+    }
+    pair->var1[pair->cnt] = besti+1;
+    pair->var2[pair->cnt] = bestj+1;
+    pair->cnt++;
+    set_remove(cand, besti);
+    set_remove(cand, bestj);
+    total_cost += maxcost;
+    }
+    set_free(cand);
+    *pair_p = pair;
+    return total_cost;
+}
+
+
+ppair pair_best_cost(cost_array_local)
+int **cost_array_local;
+{
+    ppair pair;
+    pset candidate;
+
+    best_cost = -1;
+    best_pair = NULL;
+    cost_array = cost_array_local;
+
+    pair = pair_new(cube.num_binary_vars);
+    candidate = set_full(cube.num_binary_vars);
+    generate_all_pairs(pair, cube.num_binary_vars, candidate, find_best_cost);
+    pair_free(pair);
+    set_free(candidate);
+    return best_pair;
+}
+
+
+int find_best_cost(pair)
+register ppair pair;
+{
+    register int i, cost;
+
+    cost = 0;
+    for(i = 0; i < pair->cnt; i++)
+    cost += cost_array[pair->var1[i]-1][pair->var2[i]-1];
+    if (cost > best_cost) {
+    best_cost = cost;
+    best_pair = pair_save(pair, pair->cnt);
+    }
+    if ((debug & MINCOV) && trace) {
+    printf("cost is %d ", cost);
+    print_pair(pair);
+    }
+}
+
+/*
+    pair_all: brute-force approach to try all possible pairings
+
+    pair_strategy is:
+    2) for espresso
+    3) for minimize_exact
+    4) for phase assignment
+*/
+
+pair_all(PLA, pair_strategy)
+pPLA PLA;
+int pair_strategy;
+{
+    ppair pair;
+    pset candidate;
+
+    global_PLA = PLA;
+    pair_minim_strategy = pair_strategy;
+    best_cost = PLA->F->count + 1;
+    best_pair = NULL;
+    best_phase = NULL;
+    best_F = best_D = best_R = NULL;
+    pair = pair_new(cube.num_binary_vars);
+    candidate = set_fill(set_new(cube.num_binary_vars), cube.num_binary_vars);
+
+    generate_all_pairs(pair, cube.num_binary_vars, candidate, minimize_pair);
+
+    pair_free(pair);
+    set_free(candidate);
+
+    PLA->pair = best_pair;
+    PLA->phase = best_phase;
+/* not really necessary
+    if (phase != NULL)
+    (void) set_phase(PLA->phase);
+*/
+    set_pair(PLA);
+    printf("# ");
+    print_pair(PLA->pair);
+
+    sf_free(PLA->F);
+    sf_free(PLA->D);
+    sf_free(PLA->R);
+    PLA->F = best_F;
+    PLA->D = best_D;
+    PLA->R = best_R;
+}
+
+
+/*
+ *  minimize_pair -- called as each pair is generated
+ */
+int minimize_pair(pair)
+ppair pair;
+{
+    pcover Fsave, Dsave, Rsave;
+    int i, xnum_binary_vars, xnum_vars, *xpart_size;
+
+    /* save the original covers */
+    Fsave = sf_save(global_PLA->F);
+    Dsave = sf_save(global_PLA->D);
+    Rsave = sf_save(global_PLA->R);
+
+    /* save the original cube structure */
+    xnum_binary_vars = cube.num_binary_vars;
+    xnum_vars = cube.num_vars;
+    xpart_size = ALLOC(int, cube.num_vars);
+    for(i = 0; i < cube.num_vars; i++)
+    xpart_size[i] = cube.part_size[i];
+
+    /* setup the paired variables */
+    global_PLA->pair = pair;
+    set_pair1(global_PLA, /* adjust_labels */ FALSE);
+
+    /* call the minimizer */
+    if (summary)
+    print_pair(pair);
+    switch(pair_minim_strategy) {
+    case 2:
+        EXEC_S(phase_assignment(global_PLA,0), "OPO       ", global_PLA->F);
+        if (summary)
+        printf("# phase is %s\n", pc1(global_PLA->phase));
+        break;
+    case 1:
+        EXEC_S(global_PLA->F = minimize_exact(global_PLA->F, global_PLA->D,
+        global_PLA->R, 1), "EXACT     ", global_PLA->F);
+        break;
+    case 0:
+        EXEC_S(global_PLA->F = espresso(global_PLA->F, global_PLA->D,
+        global_PLA->R), "ESPRESSO  ", global_PLA->F);
+        break;
+    default:
+        break;
+    }
+
+    /* see if we have a new best solution */
+    if (global_PLA->F->count < best_cost) {
+    best_cost = global_PLA->F->count;
+    best_pair = pair_save(pair, pair->cnt);
+    best_phase = global_PLA->phase!=NULL?set_save(global_PLA->phase):NULL;
+    if (best_F != NULL) sf_free(best_F);
+    if (best_D != NULL) sf_free(best_D);
+    if (best_R != NULL) sf_free(best_R);
+    best_F = sf_save(global_PLA->F);
+    best_D = sf_save(global_PLA->D);
+    best_R = sf_save(global_PLA->R);
+    }
+
+    /* restore the original cube structure -- free the new ones */
+    setdown_cube();
+    FREE(cube.part_size);
+    cube.num_binary_vars = xnum_binary_vars;
+    cube.num_vars = xnum_vars;
+    cube.part_size = xpart_size;
+    cube_setup();
+
+    /* restore the original cover(s) -- free the new ones */
+    sf_free(global_PLA->F);
+    sf_free(global_PLA->D);
+    sf_free(global_PLA->R);
+    global_PLA->F = Fsave;
+    global_PLA->D = Dsave;
+    global_PLA->R = Rsave;
+    global_PLA->pair = NULL;
+    global_PLA->phase = NULL;
+}
+
+generate_all_pairs(pair, n, candidate, action)
+ppair pair;
+int n;
+pset candidate;
+int (*action)();
+{
+    int i, j;
+    pset recur_candidate;
+    ppair recur_pair;
+
+    if (set_ord(candidate) < 2) {
+    (*action)(pair);
+    return;
+    }
+
+    recur_pair = pair_save(pair, n);
+    recur_candidate = set_save(candidate);
+
+    /* Find first variable still in the candidate set */
+    for(i = 0; i < n; i++)
+    if (is_in_set(candidate, i))
+        break;
+
+    /* Try all pairs of i with other variables */
+    for(j = i+1; j < n; j++)
+    if (is_in_set(candidate, j)) {
+        /* pair (i j) -- remove from candidate set for future pairings */
+        set_remove(recur_candidate, i);
+        set_remove(recur_candidate, j);
+
+        /* add to the pair array */
+        recur_pair->var1[recur_pair->cnt] = i+1;
+        recur_pair->var2[recur_pair->cnt] = j+1;
+        recur_pair->cnt++;
+
+        /* recur looking for the end ... */
+        generate_all_pairs(recur_pair, n, recur_candidate, action);
+
+        /* now break this pair, and restore candidate set */
+        recur_pair->cnt--;
+        set_insert(recur_candidate, i);
+        set_insert(recur_candidate, j);
+    }
+
+    /* if odd, generate all pairs which do NOT include i */
+    if ((set_ord(candidate) % 2) == 1) {
+    set_remove(recur_candidate, i);
+    generate_all_pairs(recur_pair, n, recur_candidate, action);
+    }
+
+    pair_free(recur_pair);
+    set_free(recur_candidate);
+}
+
+ppair pair_new(n)
+register int n;
+{
+    register ppair pair1;
+
+    pair1 = ALLOC(pair_t, 1);
+    pair1->cnt = 0;
+    pair1->var1 = ALLOC(int, n);
+    pair1->var2 = ALLOC(int, n);
+    return pair1;
+}
+
+
+ppair pair_save(pair, n)
+register ppair pair;
+register int n;
+{
+    register int k;
+    register ppair pair1;
+
+    pair1 = pair_new(n);
+    pair1->cnt = pair->cnt;
+    for(k = 0; k < pair->cnt; k++) {
+    pair1->var1[k] = pair->var1[k];
+    pair1->var2[k] = pair->var2[k];
+    }
+    return pair1;
+}
+
+
+int pair_free(pair)
+register ppair pair;
+{
+    FREE(pair->var1);
+    FREE(pair->var2);
+    FREE(pair);
+}