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https://github.com/Z3Prover/z3
synced 2025-04-08 10:25:18 +00:00
Fix unsound handling of upper bounds in wmax, thanks to Patrick Trentin for report and careful repros #847
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
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@ -93,7 +93,7 @@ private:
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mss m_mss;
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expr_ref_vector m_trail;
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strategy_t m_st;
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rational m_max_upper;
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rational m_max_upper;
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model_ref m_csmodel;
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unsigned m_correction_set_size;
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bool m_found_feasible_optimum;
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@ -109,6 +109,7 @@ private:
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bool m_pivot_on_cs; // prefer smaller correction set to core.
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bool m_dump_benchmarks; // display benchmarks (into wcnf format)
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std::string m_trace_id;
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typedef ptr_vector<expr> exprs;
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@ -150,9 +151,7 @@ public:
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return
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is_uninterp_const(l) ||
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(m.is_not(l, l) && is_uninterp_const(l));
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}
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}
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void add_soft(expr* e, rational const& w) {
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TRACE("opt", tout << mk_pp(e, m) << " |-> " << w << "\n";);
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@ -290,7 +289,7 @@ public:
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index = next_index(asms, index);
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}
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first = false;
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IF_VERBOSE(3, verbose_stream() << "weight: " << get_weight(asms[0].get()) << " " << get_weight(asms[index-1].get()) << " num soft: " << index << "\n";);
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// IF_VERBOSE(3, verbose_stream() << "weight: " << get_weight(asms[0].get()) << " " << get_weight(asms[index-1].get()) << " num soft: " << index << "\n";);
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m_last_index = index;
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is_sat = check_sat(index, asms.c_ptr());
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}
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@ -490,7 +489,7 @@ public:
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TRACE("opt", display_vec(tout << "minimized core: ", core););
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IF_VERBOSE(10, display_vec(verbose_stream() << "core: ", core););
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max_resolve(core, w);
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fml = mk_not(m, mk_and(m, m_B.size(), m_B.c_ptr()));
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fml = mk_not(m, mk_and(m, core.size(), core.c_ptr()));
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s().assert_expr(fml);
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m_lower += w;
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if (m_st == s_primal_dual) {
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@ -530,7 +529,10 @@ public:
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}
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lbool minimize_core(exprs& core) {
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if (m_c.sat_enabled() || core.empty()) {
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if (core.empty()) {
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return l_true;
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}
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if (m_c.sat_enabled()) {
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return l_true;
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}
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m_mus.reset();
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@ -607,8 +609,8 @@ public:
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// Soundness of this rule can be established using MaxRes
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//
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for (unsigned i = 1; i < core.size(); ++i) {
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expr* b_i = m_B[i-1].get();
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expr* b_i1 = m_B[i].get();
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expr* b_i = core[i-1];
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expr* b_i1 = core[i];
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if (i == 1) {
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d = to_app(b_i);
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}
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@ -658,8 +660,8 @@ public:
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// d_i => d_{i-1} or b_{i-1}
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//
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for (unsigned i = 1; i < cs.size(); ++i) {
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expr* b_i = m_B[i-1].get();
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expr* b_i1 = m_B[i].get();
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expr* b_i = cs[i - 1];
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expr* b_i1 = cs[i];
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cls = m.mk_or(b_i, d);
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if (i > 2) {
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d = mk_fresh_bool("d");
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@ -680,10 +682,11 @@ public:
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s().assert_expr(fml);
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m_defs.push_back(fml);
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new_assumption(asum, w);
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fml = m.mk_and(b_i1, cls);
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update_model(asum, fml);
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}
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fml = m.mk_or(m_B.size(), m_B.c_ptr());
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fml = m.mk_or(cs.size(), cs.c_ptr());
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s().assert_expr(fml);
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}
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@ -739,7 +742,7 @@ public:
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nsoft.push_back(mk_not(m, m_soft[i]));
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}
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fml = u.mk_lt(nsoft.size(), m_weights.c_ptr(), nsoft.c_ptr(), m_upper);
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s().assert_expr(fml);
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s().assert_expr(fml);
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}
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bool is_true(model* mdl, expr* e) {
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@ -757,10 +760,9 @@ public:
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}
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bool is_true(expr_ref_vector const& es) {
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for (unsigned i = 0; i < es.size(); ++i) {
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if (!is_true(es[i])) return false;
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}
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return true;
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unsigned i = 0;
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for (; i < es.size() && is_true(es[i]); ++i) { }
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return i == es.size();
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}
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void remove_soft(exprs const& core, expr_ref_vector& asms) {
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@ -780,7 +782,6 @@ public:
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virtual void updt_params(params_ref& p) {
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maxsmt_solver_base::updt_params(p);
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opt_params _p(p);
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m_hill_climb = _p.maxres_hill_climb();
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m_add_upper_bound_block = _p.maxres_add_upper_bound_block();
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m_max_num_cores = _p.maxres_max_num_cores();
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@ -858,7 +859,6 @@ public:
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IF_VERBOSE(0, verbose_stream() << "assignment is infeasible\n";);
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}
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}
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};
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opt::maxsmt_solver_base* opt::mk_maxres(
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@ -62,20 +62,21 @@ namespace opt {
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}
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m_upper = m_lower;
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bool was_sat = false;
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expr_ref_vector disj(m), asms(m);
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expr_ref_vector asms(m);
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vector<expr_ref_vector> cores;
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obj_map<expr, rational>::iterator it = soft.begin(), end = soft.end();
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for (; it != end; ++it) {
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expr* c = assert_weighted(wth(), it->m_key, it->m_value);
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if (!is_true(it->m_key)) {
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disj.push_back(m.mk_not(c));
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m_upper += it->m_value;
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}
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}
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wth().init_min_cost(m_upper - m_lower);
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s().assert_expr(mk_or(disj));
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trace_bounds("wmax");
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TRACE("opt",
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s().display(tout); tout << "\n";
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tout << "lower: " << m_lower << " upper: " << m_upper << "\n";);
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while (!m.canceled() && m_lower < m_upper) {
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//mk_assumptions(asms);
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//is_sat = s().preferred_sat(asms, cores);
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@ -84,6 +85,7 @@ namespace opt {
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is_sat = l_undef;
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}
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if (is_sat == l_false) {
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TRACE("opt", tout << "Unsat\n";);
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break;
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}
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if (is_sat == l_true) {
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@ -211,7 +211,7 @@ namespace sat {
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if (propagate_bin_clause(l1, l2)) {
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if (scope_lvl() == 0)
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return;
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if (!learned)
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if (!learned)
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m_clauses_to_reinit.push_back(clause_wrapper(l1, l2));
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}
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m_stats.m_mk_bin_clause++;
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@ -234,19 +234,18 @@ namespace sat {
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}
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void solver::push_reinit_stack(clause & c) {
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TRACE("sat_reinit", tout << "adding to reinit stack: " << c << "\n";);
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m_clauses_to_reinit.push_back(clause_wrapper(c));
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c.set_reinit_stack(true);
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c.set_reinit_stack(true);
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}
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clause * solver::mk_ter_clause(literal * lits, bool learned) {
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m_stats.m_mk_ter_clause++;
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clause * r = m_cls_allocator.mk_clause(3, lits, learned);
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bool reinit;
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attach_ter_clause(*r, reinit);
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if (!learned && reinit) {
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TRACE("sat_reinit", tout << "adding to reinit stack: " << *r << "\n";);
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push_reinit_stack(*r);
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}
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bool reinit = attach_ter_clause(*r);
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if (reinit && !learned) push_reinit_stack(*r);
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if (learned)
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m_learned.push_back(r);
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else
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@ -254,8 +253,8 @@ namespace sat {
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return r;
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}
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void solver::attach_ter_clause(clause & c, bool & reinit) {
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reinit = false;
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bool solver::attach_ter_clause(clause & c) {
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bool reinit = false;
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m_watches[(~c[0]).index()].push_back(watched(c[1], c[2]));
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m_watches[(~c[1]).index()].push_back(watched(c[0], c[2]));
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m_watches[(~c[2]).index()].push_back(watched(c[0], c[1]));
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@ -276,18 +275,15 @@ namespace sat {
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reinit = true;
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}
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}
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return reinit;
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}
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clause * solver::mk_nary_clause(unsigned num_lits, literal * lits, bool learned) {
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m_stats.m_mk_clause++;
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clause * r = m_cls_allocator.mk_clause(num_lits, lits, learned);
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SASSERT(!learned || r->is_learned());
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bool reinit;
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attach_nary_clause(*r, reinit);
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if (!learned && reinit) {
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TRACE("sat_reinit", tout << "adding to reinit stack: " << *r << "\n";);
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push_reinit_stack(*r);
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}
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bool reinit = attach_nary_clause(*r);
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if (reinit && !learned) push_reinit_stack(*r);
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if (learned)
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m_learned.push_back(r);
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else
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return r;
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}
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void solver::attach_nary_clause(clause & c, bool & reinit) {
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reinit = false;
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bool solver::attach_nary_clause(clause & c) {
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bool reinit = false;
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clause_offset cls_off = m_cls_allocator.get_offset(&c);
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if (scope_lvl() > 0) {
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if (c.is_learned()) {
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@ -325,15 +321,16 @@ namespace sat {
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literal block_lit = c[some_idx];
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m_watches[(~c[0]).index()].push_back(watched(block_lit, cls_off));
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m_watches[(~c[1]).index()].push_back(watched(block_lit, cls_off));
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return reinit;
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}
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void solver::attach_clause(clause & c, bool & reinit) {
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SASSERT(c.size() > 2);
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reinit = false;
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if (c.size() == 3)
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attach_ter_clause(c, reinit);
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reinit = attach_ter_clause(c);
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else
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attach_nary_clause(c, reinit);
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reinit = attach_nary_clause(c);
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}
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/**
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@ -184,11 +184,9 @@ namespace sat {
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void mk_bin_clause(literal l1, literal l2, bool learned);
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bool propagate_bin_clause(literal l1, literal l2);
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clause * mk_ter_clause(literal * lits, bool learned);
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void attach_ter_clause(clause & c, bool & reinit);
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void attach_ter_clause(clause & c) { bool reinit; attach_ter_clause(c, reinit); }
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bool attach_ter_clause(clause & c);
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clause * mk_nary_clause(unsigned num_lits, literal * lits, bool learned);
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void attach_nary_clause(clause & c, bool & reinit);
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void attach_nary_clause(clause & c) { bool reinit; attach_nary_clause(c, reinit); }
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bool attach_nary_clause(clause & c);
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void attach_clause(clause & c, bool & reinit);
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void attach_clause(clause & c) { bool reinit; attach_clause(c, reinit); }
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unsigned select_watch_lit(clause const & cls, unsigned starting_at) const;
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@ -180,7 +180,7 @@ namespace smt {
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final_check_status theory_wmaxsat::final_check_eh() {
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if (m_normalize) normalize();
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// std::cout << "cost: " << m_zcost << " min cost: " << m_zmin_cost << "\n";
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TRACE("opt", tout << "cost: " << m_zcost << " min cost: " << m_zmin_cost << "\n";);
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return FC_DONE;
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}
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