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https://github.com/Z3Prover/z3
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walk/gsat
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
1e32f1fbb5
commit
d819784500
3 changed files with 189 additions and 21 deletions
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@ -34,7 +34,7 @@ project(Z3 C CXX)
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set(Z3_VERSION_MAJOR 4)
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set(Z3_VERSION_MINOR 5)
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set(Z3_VERSION_PATCH 1)
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set(Z3_VERSION_TWEAK 0)
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set(Z3_VERSION_TWEAK 0303)
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set(Z3_FULL_VERSION 0)
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set(Z3_VERSION "${Z3_VERSION_MAJOR}.${Z3_VERSION_MINOR}.${Z3_VERSION_PATCH}.${Z3_VERSION_TWEAK}")
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message(STATUS "Z3 version ${Z3_VERSION}")
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@ -187,6 +187,13 @@ namespace sat {
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}
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}
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void local_search::verify_unsat_stack() const {
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for (unsigned i = 0; i < m_unsat_stack.size(); ++i) {
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constraint const& c = m_constraints[m_unsat_stack[i]];
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SASSERT(c.m_k < constraint_value(c));
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}
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}
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unsigned local_search::constraint_value(constraint const& c) const {
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unsigned value = 0;
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for (unsigned i = 0; i < c.size(); ++i) {
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@ -226,7 +233,6 @@ namespace sat {
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local_search::local_search(solver& s) :
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m_par(0) {
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std::cout << "Parameter1: " << s.m_config.m_local_search_parameter1 << "\n";
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m_vars.reserve(s.num_vars());
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// copy units
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@ -322,15 +328,28 @@ namespace sat {
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lbool local_search::check() {
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return check(0, 0);
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}
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lbool local_search::check(unsigned sz, literal const* assumptions, parallel* p) {
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flet<parallel*> _p(m_par, p);
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m_model.reset();
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unsigned num_constraints = m_constraints.size();
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for (unsigned i = 0; i < sz; ++i) {
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add_clause(1, assumptions + i);
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void local_search::walksat() {
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reinit();
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timer timer;
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timer.start();
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unsigned step = 0, total_steps = 0, max_steps = (1 << 20);
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for (unsigned tries = 1; !m_unsat_stack.empty() && m_limit.inc(); ++tries) {
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for (step = 0; step < max_steps && !m_unsat_stack.empty(); ++step) {
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pick_flip_walksat();
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}
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total_steps += step;
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if (tries % 10 == 0) {
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IF_VERBOSE(1, verbose_stream() << "(sat-local-search"
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<< " :tries " << tries
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<< " :steps " << total_steps
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<< " :unsat " << m_unsat_stack.size()
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<< " :time " << timer.get_seconds() << ")\n";);
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}
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}
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init();
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}
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void local_search::gsat() {
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reinit();
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bool reach_known_best_value = false;
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bool_var flipvar;
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@ -347,8 +366,8 @@ namespace sat {
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break;
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}
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}
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flipvar = pick_var();
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flip(flipvar);
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flipvar = pick_var_gsat();
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flip_gsat(flipvar);
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m_vars[flipvar].m_time_stamp = step;
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}
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IF_VERBOSE(1, if (tries % 10 == 0)
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@ -363,6 +382,26 @@ namespace sat {
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m_par->get_phase(*this);
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}
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}
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}
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lbool local_search::check(unsigned sz, literal const* assumptions, parallel* p) {
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flet<parallel*> _p(m_par, p);
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m_model.reset();
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unsigned num_constraints = m_constraints.size();
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for (unsigned i = 0; i < sz; ++i) {
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add_clause(1, assumptions + i);
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}
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init();
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switch (m_config.mode()) {
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case local_search_mode::gsat:
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gsat();
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break;
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case local_search_mode::wsat:
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walksat();
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break;
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}
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// remove unit clauses from assumptions.
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m_constraints.shrink(num_constraints);
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@ -398,7 +437,111 @@ namespace sat {
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m_unsat_stack.push_back(c);
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}
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void local_search::flip(bool_var flipvar)
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void local_search::pick_flip_walksat() {
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m_good_vars.reset();
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bool_var v;
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constraint const& c = m_constraints[m_unsat_stack[m_rand() % m_unsat_stack.size()]];
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SASSERT(c.m_k < constraint_value(c));
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if (m_rand() % 100 < 5) {
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// display(std::cout, c);
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unsigned best_bsb = 0;
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// find the first one, to fast break the rest
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unsigned i = 0;
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while (true) {
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v = c[i].var();
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if (is_true(c[i])) {
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bool tt = cur_solution(v);
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int_vector const& falsep = m_vars[v].m_watch[!tt];
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for (unsigned j = 0; j < falsep.size(); ++j) {
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unsigned ci = falsep[j];
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if (constraint_slack(ci) < 0)
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++best_bsb;
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else if (constraint_slack(ci) == 0)
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// >= unsat_stack_fill_pointer is enough
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best_bsb += m_constraints.size();
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}
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break;
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}
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++i;
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}
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m_good_vars.push_back(v);
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for (++i; i < c.size(); ++i) {
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v = c[i].var();
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if (is_true(c[i])) {
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bool found = false;
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unsigned bsb = 0;
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bool tt = cur_solution(v);
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int_vector const& falsep = m_vars[v].m_watch[!tt];
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for (unsigned j = 0; j < falsep.size() && !found; ++j) {
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unsigned ci = falsep[j];
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if (constraint_slack(ci) < 0) {
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if (bsb == best_bsb) {
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found = true;
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}
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else {
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++bsb;
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}
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}
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else if (constraint_slack(ci) == 0) {
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// >= unsat_stack_fill_pointer is enough
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bsb += m_constraints.size();
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if (bsb > best_bsb) {
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found = true;
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}
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}
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}
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if (!found) {
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if (bsb < best_bsb) {
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best_bsb = bsb;
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m_good_vars.reset();
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m_good_vars.push_back(v);
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}
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else {// if (bb == best_bb)
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m_good_vars.push_back(v);
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}
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}
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}
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}
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}
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else {
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for (unsigned i = 0; i < c.size(); ++i) {
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if (is_true(c[i]))
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m_good_vars.push_back(c[i].var());
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}
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}
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SASSERT(!m_good_vars.empty());
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//std::cout << m_good_vars.size() << "\n";
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flip_walksat(m_good_vars[m_rand() % m_good_vars.size()]);
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}
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void local_search::flip_walksat(bool_var flipvar) {
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m_vars[flipvar].m_value = !cur_solution(flipvar);
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bool flip_is_true = cur_solution(flipvar);
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int_vector& truep = m_vars[flipvar].m_watch[flip_is_true];
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int_vector& falsep = m_vars[flipvar].m_watch[!flip_is_true];
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for (unsigned i = 0; i < truep.size(); ++i) {
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unsigned ci = truep[i];
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constraint& c = m_constraints[ci];
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--c.m_slack;
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if (c.m_slack == -1) { // from 0 to -1: sat -> unsat
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unsat(ci);
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}
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}
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for (unsigned i = 0; i < falsep.size(); ++i) {
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unsigned ci = falsep[i];
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constraint& c = m_constraints[ci];
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++c.m_slack;
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if (c.m_slack == 0) { // from -1 to 0: unsat -> sat
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sat(ci);
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}
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}
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// verify_unsat_stack();
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}
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void local_search::flip_gsat(bool_var flipvar)
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{
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// already changed truth value!!!!
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m_vars[flipvar].m_value = !cur_solution(flipvar);
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@ -558,7 +701,7 @@ namespace sat {
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(time_stamp(v) < time_stamp(best_var))))))));
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}
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bool_var local_search::pick_var() {
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bool_var local_search::pick_var_gsat() {
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bool_var best_var = m_vars.size()-1; // sentinel variable
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// SAT Mode
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if (m_unsat_stack.empty()) {
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@ -613,7 +756,6 @@ namespace sat {
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TRACE("sat",
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tout << "seed:\t" << m_config.seed() << '\n';
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tout << "cutoff time:\t" << m_config.cutoff_time() << '\n';
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tout << "strategy id:\t" << m_config.strategy_id() << '\n';
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tout << "best_known_value:\t" << m_config.best_known_value() << '\n';
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tout << "max_steps:\t" << max_steps << '\n';
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@ -622,7 +764,12 @@ namespace sat {
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void local_search::print_info(std::ostream& out) {
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for (unsigned v = 0; v < num_vars(); ++v) {
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out << "v" << v << "\t" << m_vars[v].m_neighbors.size() << '\t' << cur_solution(v) << '\t' << conf_change(v) << '\t' << score(v) << '\t' << slack_score(v) << '\n';
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out << "v" << v << "\t"
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<< m_vars[v].m_neighbors.size() << '\t'
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<< cur_solution(v) << '\t'
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<< conf_change(v) << '\t'
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<< score(v) << '\t'
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<< slack_score(v) << '\n';
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}
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}
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@ -27,25 +27,33 @@ namespace sat {
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class parallel;
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enum local_search_mode {
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gsat,
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wsat
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};
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class local_search_config {
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unsigned m_seed;
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unsigned m_strategy_id;
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int m_best_known_value;
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local_search_mode m_mode;
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public:
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local_search_config()
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{
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local_search_config() {
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m_seed = 0;
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m_strategy_id = 0;
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m_best_known_value = INT_MAX;
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m_mode = local_search_mode::wsat;
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}
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unsigned seed() const { return m_seed; }
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unsigned strategy_id() const { return m_strategy_id; }
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unsigned best_known_value() const { return m_best_known_value; }
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local_search_mode mode() const { return m_mode; }
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void set_seed(unsigned s) { m_seed = s; }
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void set_strategy_id(unsigned i) { m_strategy_id = i; }
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void set_best_known_value(unsigned v) { m_best_known_value = v; }
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void set_mode(local_search_mode m) { m_mode = m; }
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};
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@ -131,7 +139,8 @@ namespace sat {
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unsigned num_constraints() const { return m_constraints.size(); } // constraint index from 1 to num_constraint
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unsigned constraint_slack(unsigned ci) const { return m_constraints[ci].m_slack; }
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// int_vector nb_slack; // constraint_k - ob_var(same in ob) - none_ob_true_terms_count. if < 0: some ob var might be flipped to false, result in an ob decreasing
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// bool_vector has_true_ob_terms;
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@ -142,6 +151,8 @@ namespace sat {
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// configuration changed decreasing variables (score>0 and conf_change==true)
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int_vector goodvar_stack;
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svector<bool_var> m_good_vars; // candidate variables to flip on.
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// information about solution
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int objective_value; // the objective function value corresponds to the current solution
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bool_vector best_solution; // !var: the best solution so far
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@ -167,9 +178,17 @@ namespace sat {
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void init_scores();
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void init_goodvars();
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bool_var pick_var();
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bool_var pick_var_gsat();
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void flip(bool_var v);
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void flip_gsat(bool_var v);
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void pick_flip_walksat();
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void flip_walksat(bool_var v);
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void walksat();
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void gsat();
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void unsat(unsigned c);
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@ -187,6 +206,8 @@ namespace sat {
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void verify_solution() const;
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void verify_unsat_stack() const;
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void verify_constraint(constraint const& c) const;
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unsigned constraint_value(constraint const& c) const;
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