/*
* Bounded search: search until the conflict bound is reached
* or until the problem is solved.
* - reduce_threshold: number of learned clauses above which reduce_clause_database is called
* - r_factor = increment factor for reduce threshold
*/
static void sat_search(smt_core_t *core, uint32_t conflict_bound, uint32_t *reduce_threshold, double r_factor) {
uint64_t max_conflicts;
uint32_t r_threshold;
literal_t l;
assert(smt_status(core) == STATUS_SEARCHING || smt_status(core) == STATUS_INTERRUPTED);
max_conflicts = num_conflicts(core) + conflict_bound;
r_threshold = *reduce_threshold;
smt_process(core);
while (smt_status(core) == STATUS_SEARCHING && num_conflicts(core) <= max_conflicts) {
// reduce heuristic
if (num_learned_clauses(core) >= r_threshold) {
reduce_clause_database(core);
r_threshold = (uint32_t) (r_threshold * r_factor);
}
// decision
l = select_unassigned_literal(core);
if (l == null_literal) {
// all variables assigned: the problem is satisfiable
end_search_sat(core);
break;
}
// propagation
decide_literal(core, l);
smt_process(core);
}
*reduce_threshold = r_threshold;
}
/*
* Full header: includes the learned clauses
*/
static void dimacs_print_full_header(FILE *f, smt_core_t *core) {
uint32_t num_clauses;
num_clauses = num_empty_clauses(core) + num_unit_clauses(core) + num_binary_clauses(core) +
num_prob_clauses(core) + num_learned_clauses(core) + 1;
fprintf(f, "p cnf %"PRIu32" %"PRIu32"\n", core->nvars, num_clauses);
}
/*
* Print some statistic data + header if requested (on stdout)
*/
static void show_progress(smt_core_t *core,
uint32_t restart_threshold, uint32_t reduce_threshold, bool show_header) {
if (show_header) {
printf("---------------------------------------------------------------------------------\n");
printf("| Thresholds | Binary | Original | Learned |\n");
printf("| Conf. Del. | Clauses | Clauses Lits. | Clauses Lits. Lits/Cl. |\n");
printf("---------------------------------------------------------------------------------\n");
}
printf("| %7"PRIu32" %8"PRIu32" | %8"PRIu32" | %8"PRIu32" %8"PRIu64" | %8"PRIu32" %8"PRIu64" %7.1f |\n",
restart_threshold, reduce_threshold,
num_binary_clauses(core),
num_prob_clauses(core), num_prob_literals(core),
num_learned_clauses(core), num_learned_literals(core),
((double) num_learned_literals(core)/num_learned_clauses(core)));
fflush(stdout);
}