//returns 1 if all the clauses mentioning the variable are subsumed, 0 otherwise
BOOLEAN sat_irrelevant_var(const Var* var) {
for (c2dSize i = 0; i < sat_var_occurences(var); i++) {
if (!sat_subsumed_clause(var->clauses[i]))
return 0;
}
return 1;
}
//returns 1 if all the clauses mentioning the variable are subsumed, 0 otherwise
BOOLEAN sat_irrelevant_var(const Var* var) {
c2dSize occurences = sat_var_occurences(var);
for (c2dSize i = 0; i < occurences; i++) {
Clause* clause = sat_clause_of_var(i, var);
if (!sat_subsumed_clause(clause))
return 0;
}
return 1;
}
void sat_restore_literal(SatState* sat_state, Lit* lit) {
lit->implied = 0;
Var* var = sat_literal_var(lit);
for (c2dSize i = 0; i < sat_var_occurences(var); i++) {
Clause* clause = sat_clause_of_var(i, var);
if (sat_subsumed_clause(clause)) {
clause->subsumed = sat_check_subsumed_clause(clause);
if (!sat_subsumed_clause(clause))
vector_push(&sat_state->q, clause);
}
}
for (c2dSize i = 0; i < vector_size(&var->mentions_lc); i++) {
Clause* clause = vector_get(&var->mentions_lc, i);
if (sat_subsumed_clause(clause)) {
clause->subsumed = sat_check_subsumed_clause(clause);
if (!sat_subsumed_clause(clause))
vector_push(&sat_state->q, clause);
}
}
}
//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;
}
