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https://github.com/Z3Prover/z3
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working on adding basic cores to efficient SAT solver
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
96dc933c99
commit
e98acf4ece
8 changed files with 203 additions and 30 deletions
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@ -685,8 +685,8 @@ namespace sat {
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// Search
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//
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// -----------------------
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lbool solver::check() {
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IF_VERBOSE(2, verbose_stream() << "(sat.sat-solver using the new SAT solver)\n";);
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lbool solver::check(unsigned num_lits, literal const* lits) {
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IF_VERBOSE(2, verbose_stream() << "(sat.sat-solver using the efficient SAT solver)\n";);
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SASSERT(scope_lvl() == 0);
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#ifdef CLONE_BEFORE_SOLVING
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if (m_mc.empty()) {
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@ -697,6 +697,7 @@ namespace sat {
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try {
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if (inconsistent()) return l_false;
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init_search();
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init_assumptions(num_lits, lits);
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propagate(false);
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if (inconsistent()) return l_false;
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cleanup();
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@ -706,6 +707,7 @@ namespace sat {
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if (r != l_undef)
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return r;
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pop(scope_lvl());
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reinit_assumptions();
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m_conflicts_since_restart = 0;
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m_restart_threshold = m_config.m_restart_initial;
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}
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@ -851,6 +853,40 @@ namespace sat {
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}
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}
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void solver::init_assumptions(unsigned num_lits, literal const* lits) {
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if (num_lits == 0) {
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return;
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}
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push();
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m_assumptions.reset();
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m_assumption_set.reset();
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for (unsigned i = 0; i < num_lits; ++i) {
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literal l = lits[i];
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SASSERT(is_external(l.var()));
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m_assumption_set.insert(l);
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m_assumptions.push_back(l);
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mk_clause(1, &l);
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}
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}
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void solver::reinit_assumptions() {
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if (tracking_assumptions()) {
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push();
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for (unsigned i = 0; i < m_assumptions.size(); ++i) {
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literal l = m_assumptions[i];
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mk_clause(1, &l);
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}
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}
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}
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bool solver::tracking_assumptions() const {
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return !m_assumptions.empty();
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}
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bool solver::is_assumption(literal l) const {
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return tracking_assumptions() && m_assumption_set.contains(l);
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}
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void solver::init_search() {
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m_phase_counter = 0;
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m_phase_cache_on = false;
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@ -986,6 +1022,7 @@ namespace sat {
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<< " :time " << std::fixed << std::setprecision(2) << m_stopwatch.get_current_seconds() << ")\n";);
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IF_VERBOSE(30, display_status(verbose_stream()););
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pop(scope_lvl());
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reinit_assumptions();
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m_conflicts_since_restart = 0;
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switch (m_config.m_restart) {
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case RS_GEOMETRIC:
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@ -1305,7 +1342,7 @@ namespace sat {
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bool solver::resolve_conflict() {
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while (true) {
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bool r = resolve_conflict_core();
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bool r = resolve_conflict_core(false);
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CASSERT("sat_check_marks", check_marks());
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// after pop, clauses are reinitialized, this may trigger another conflict.
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if (!r)
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@ -1315,7 +1352,7 @@ namespace sat {
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}
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}
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bool solver::resolve_conflict_core() {
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bool solver::resolve_conflict_core(bool generate_core) {
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TRACE("sat_conflict", tout << "conflict detected\n";);
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m_stats.m_conflict++;
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@ -1324,8 +1361,21 @@ namespace sat {
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m_conflicts_since_gc++;
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m_conflict_lvl = get_max_lvl(m_not_l, m_conflict);
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if (m_conflict_lvl == 0)
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if (!generate_core && m_conflict_lvl <= 1 && tracking_assumptions()) {
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resolve_conflict_core(true);
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m_core.reset();
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for (unsigned i = 0; i < m_lemma.size(); ++i) {
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literal l = ~m_lemma[i];
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if (is_assumption(l)) {
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m_core.push_back(l);
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}
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}
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return false;
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}
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if (m_conflict_lvl == 0) {
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return false;
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}
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m_lemma.reset();
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forget_phase_of_vars(m_conflict_lvl);
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@ -1337,7 +1387,7 @@ namespace sat {
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unsigned num_marks = 0;
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if (m_not_l != null_literal) {
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TRACE("sat_conflict", tout << "not_l: " << m_not_l << "\n";);
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process_antecedent(m_not_l, num_marks);
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process_antecedent(generate_core, m_not_l, num_marks);
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}
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literal consequent = m_not_l;
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@ -1350,11 +1400,11 @@ namespace sat {
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case justification::NONE:
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break;
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case justification::BINARY:
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process_antecedent(~(js.get_literal()), num_marks);
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process_antecedent(generate_core, ~(js.get_literal()), num_marks);
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break;
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case justification::TERNARY:
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process_antecedent(~(js.get_literal1()), num_marks);
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process_antecedent(~(js.get_literal2()), num_marks);
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process_antecedent(generate_core, ~(js.get_literal1()), num_marks);
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process_antecedent(generate_core, ~(js.get_literal2()), num_marks);
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break;
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case justification::CLAUSE: {
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clause & c = *(m_cls_allocator.get_clause(js.get_clause_offset()));
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@ -1365,13 +1415,13 @@ namespace sat {
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i = 1;
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}
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else {
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process_antecedent(~c[0], num_marks);
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process_antecedent(generate_core, ~c[0], num_marks);
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i = 2;
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}
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}
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unsigned sz = c.size();
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for (; i < sz; i++)
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process_antecedent(~c[i], num_marks);
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process_antecedent(generate_core, ~c[i], num_marks);
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break;
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}
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case justification::EXT_JUSTIFICATION: {
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@ -1379,7 +1429,7 @@ namespace sat {
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literal_vector::iterator it = m_ext_antecedents.begin();
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literal_vector::iterator end = m_ext_antecedents.end();
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for (; it != end; ++it)
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process_antecedent(*it, num_marks);
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process_antecedent(generate_core, *it, num_marks);
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break;
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}
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default:
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@ -1408,7 +1458,7 @@ namespace sat {
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m_lemma[0] = ~consequent;
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TRACE("sat_lemma", tout << "new lemma size: " << m_lemma.size() << "\n" << m_lemma << "\n";);
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if (m_config.m_minimize_lemmas) {
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if (m_config.m_minimize_lemmas && !generate_core) {
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minimize_lemma();
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reset_lemma_var_marks();
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if (m_config.m_dyn_sub_res)
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@ -1431,15 +1481,24 @@ namespace sat {
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pop(m_scope_lvl - new_scope_lvl);
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TRACE("sat_conflict_detail", display(tout); tout << "assignment:\n"; display_assignment(tout););
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clause * lemma = mk_clause_core(m_lemma.size(), m_lemma.c_ptr(), true);
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if (lemma) {
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lemma->set_glue(glue);
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if (!generate_core) {
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clause * lemma = mk_clause_core(m_lemma.size(), m_lemma.c_ptr(), true);
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if (lemma) {
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lemma->set_glue(glue);
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}
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}
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decay_activity();
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updt_phase_counters();
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return true;
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}
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void solver::mk_unsat_core() {
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m_core.reset();
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m_not_l;
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m_conflict;
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}
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unsigned solver::get_max_lvl(literal consequent, justification js) {
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if (!m_ext)
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return scope_lvl();
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@ -1514,14 +1573,14 @@ namespace sat {
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return idx;
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}
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void solver::process_antecedent(literal antecedent, unsigned & num_marks) {
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void solver::process_antecedent(bool generate_core, literal antecedent, unsigned & num_marks) {
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bool_var var = antecedent.var();
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unsigned var_lvl = lvl(var);
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SASSERT(var < num_vars());
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if (!is_marked(var) && var_lvl > 0) {
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mark(var);
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inc_activity(var);
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if (var_lvl == m_conflict_lvl)
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if (var_lvl == m_conflict_lvl && !generate_core)
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num_marks++;
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else
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m_lemma.push_back(~antecedent);
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