//frees the SatState
void sat_state_free(SatState* sat_state) {
for (c2dSize i = 1; i <= sat_var_count(sat_state); i++) {
Var* var = sat_index2var(i, sat_state);
vector_free(&var->mentions);
vector_free(&var->mentions_lc);
free(var);
free(sat_index2literal(i, sat_state));
free(sat_index2literal(-i, sat_state));
}
for (c2dSize i = 1; i <= sat_clause_count(sat_state); i++) {
Clause* clause = sat_index2clause(i, sat_state);
vector_free(&clause->lits);
free(clause);
}
vector_free(&sat_state->vars);
vector_free(&sat_state->plits);
vector_free(&sat_state->nlits);
vector_free(&sat_state->kb);
vector_free(&sat_state->lc);
vector_free(&sat_state->ds);
vector_free(&sat_state->il);
vector_free(&sat_state->q);
vector_free(&sat_state->s);
free(sat_state);
}
//applies unit resolution to the cnf of sat state
//returns 1 if unit resolution succeeds, 0 if it finds a contradiction
BOOLEAN sat_unit_resolution(SatState* sat_state) {
BOOLEAN more = 1;
while (more) {
more = 0;
for (c2dSize i = vector_size(&sat_state->q); i >= 1; i--) {
Clause* clause = vector_get(&sat_state->q, i - 1);
clause->subsumed = sat_check_subsumed_clause(clause);
if (sat_subsumed_clause(clause)) {
vector_erase(&sat_state->q, i - 1);
continue;
}
BOOLEAN flag = 0;
c2dSize pos;
for (c2dSize j = 0; j < sat_clause_size(clause); j++) {
Lit* lit = vector_get(&clause->lits, j);
if (!sat_implied_literal(sat_opp_literal(lit))) {
flag++;
pos = j;
if (flag == 2)
break;
}
}
if (flag == 0) {
sat_state->ac = malloc(sizeof(Clause));
vector_init(&sat_state->ac->lits);
sat_state->ac->subsumed = 0;
sat_state->ac->mark = 0;
if (vector_size(&sat_state->ds) > 0) {
for (c2dSize j = 0; j < sat_var_count(sat_state); j++) {
Var* var = vector_get(&sat_state->vars, j);
var->u = var->level <= 1;
}
sat_get_assert_clause(sat_state, sat_state->ac, clause->index - 1, 0,
vector_size(&sat_state->s) - 1);
}
return 0;
}
if (flag == 1) {
Lit* lit = vector_get(&clause->lits, pos);
lit->implied = 1;
lit->locate = clause->index - 1;
lit->var->level = vector_size(&sat_state->ds) + 1;
vector_push(&sat_state->il, lit);
vector_push(&sat_state->s, lit);
clause->subsumed = 1;
vector_erase(&sat_state->q, i - 1);
more = 1;
}
}
}
return 1;
}
//returns a variable structure for the corresponding index
Var* sat_index2var(c2dSize index, const SatState* sat_state) {
ASSERT_TEST(index>=1 && index<=sat_var_count(sat_state)); //index range test
return sat_state->variables[index-1];
}
//constructs a SatState from an input cnf file
SatState* sat_state_new(const char* file_name) {
FILE *file;
if (!(file = fopen(file_name, "r")))
return NULL;
SatState *sat_state = malloc(sizeof(SatState));
while (!feof(file)) {
if (fgetc(file) == 'p')
break;
while (fgetc(file) != '\n')
continue;
}
fscanf(file, " cnf %lu %lu", &sat_state->varnum, &sat_state->clausenum);
vector_init(&sat_state->vars);
vector_init(&sat_state->plits);
vector_init(&sat_state->nlits);
vector_init(&sat_state->kb);
vector_init(&sat_state->lc);
vector_init(&sat_state->ds);
vector_init(&sat_state->il);
vector_init(&sat_state->q);
vector_init(&sat_state->s);
sat_state->ac = NULL;
for (c2dSize i = 1; i <= sat_var_count(sat_state); i++) {
Var* var = malloc(sizeof(Var));
var->index = i;
var->mark = 0;
vector_init(&var->mentions);
vector_init(&var->mentions_lc);
Lit* plit = malloc(sizeof(Lit));
plit->index = i;
plit->implied = 0;
plit->var = var;
Lit* nlit = malloc(sizeof(Lit));
nlit->index = -i;
nlit->implied = 0;
nlit->var = var;
vector_push(&sat_state->plits, plit);
vector_push(&sat_state->nlits, nlit);
var->plit = plit;
var->nlit = nlit;
vector_push(&sat_state->vars, var);
}
for (c2dSize i = 1; i <= sat_clause_count(sat_state); i++) {
Clause* clause = malloc(sizeof(Clause));
clause->index = i;
clause->subsumed = 0;
clause->mark = 0;
vector_init(&clause->lits);
while (1) {
c2dLiteral index;
while (!fscanf(file, "%ld", &index) || (index == 0 && vector_size(&clause->lits) == 0)) {
while (fgetc(file) != '\n')
continue;
}
if (index == 0)
break;
vector_push(&clause->lits, sat_index2literal(index, sat_state));
}
vector_push(&sat_state->kb, clause);
vector_push(&sat_state->q, clause);
}
for (c2dSize i = 1; i <= sat_clause_count(sat_state); i++) {
Clause* clause = sat_index2clause(i, sat_state);
for (c2dSize j = 0; j < sat_clause_size(clause); j++) {
Lit* lit = vector_get(&clause->lits, j);
Var* var = sat_literal_var(lit);
if (vector_size(&var->mentions) == 0 || vector_top(&var->mentions) != clause)
vector_push(&var->mentions, clause);
}
}
fclose(file);
return sat_state;
}
