mirror of
https://github.com/Z3Prover/z3
synced 2025-04-28 03:15:50 +00:00
Nikolaj Bjorner
GitHub
commit
2eea7709e0
4 changed files with 44 additions and 139 deletions
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@ -2938,7 +2938,7 @@ expr_ref context::mk_unsat_answer() const
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}
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proof_ref context::get_ground_refutation() {
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proof_ref context::get_ground_refutation() const {
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if (m_last_result != l_true) {
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IF_VERBOSE(0, verbose_stream()
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<< "Sat answer unavailable when result is false\n";);
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@ -2948,142 +2948,45 @@ proof_ref context::get_ground_refutation() {
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ground_sat_answer_op op(*this);
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return op(*m_query);
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}
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expr_ref context::get_ground_sat_answer() {
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expr_ref context::get_ground_sat_answer() const {
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if (m_last_result != l_true) {
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IF_VERBOSE(0, verbose_stream()
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<< "Sat answer unavailable when result is false\n";);
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return expr_ref(m);
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}
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// treat the following as queues: read from left to right and insert at the right
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reach_fact_ref_vector reach_facts;
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ptr_vector<func_decl> preds;
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ptr_vector<pred_transformer> pts;
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expr_ref_vector cex (m); // pre-order list of ground instances of predicates
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expr_ref_vector cex_facts (m); // equalities for the ground cex using signature constants
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// convert a ground refutation into a linear counterexample
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// only works for linear CHC systems
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expr_ref_vector cex(m);
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proof_ref pf = get_ground_refutation();
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// temporary
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reach_fact *reach_fact;
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pred_transformer* pt;
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expr_ref cex_fact (m);
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datalog::rule const* r;
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// get and discard query rule
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reach_fact = m_query->get_last_rf ();
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r = &reach_fact->get_rule ();
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// initialize queues
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reach_facts.append (reach_fact->get_justifications ());
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if (reach_facts.size() != 1) {
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// XXX Escape if an assertion is about to fail
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IF_VERBOSE(1,
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verbose_stream () <<
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"Warning: counterexample is trivial or non-existent\n";);
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return expr_ref(m.mk_true(), m);
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proof_ref_vector premises(m);
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expr_ref conclusion(m);
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svector<std::pair<unsigned, unsigned>> positions;
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vector<expr_ref_vector> substs;
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unsigned count = 0;
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while (m.is_hyper_resolve(pf, premises, conclusion, positions, substs)) {
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// skip the first fact since it is query!X introduced by the encoding
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// and not a user-visible predicate
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if (count++ > 0)
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cex.push_back(m.get_fact(pf));
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if (premises.size() > 1) {
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SASSERT(premises.size() == 2 && "Non linear CHC detected");
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pf = premises.get(1);
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} else {
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pf.reset();
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break;
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}
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m_query->find_predecessors (*r, preds);
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SASSERT (preds.size () == 1);
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pts.push_back (&(get_pred_transformer (preds[0])));
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cex_facts.push_back (m.mk_true ());
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// XXX a hack to avoid assertion when query predicate is not nullary
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if (preds[0]->get_arity () == 0)
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{ cex.push_back(m.mk_const(preds[0])); }
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// smt context to obtain local cexes
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ref<solver> cex_ctx =
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mk_smt_solver(m, params_ref::get_empty(), symbol::null);
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bool first = true;
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// preorder traversal of the query derivation tree
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for (unsigned curr = 0; curr < pts.size (); curr++) {
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// pick next pt, fact, and cex_fact
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pt = pts.get (curr);
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reach_fact = reach_facts[curr];
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cex_fact = cex_facts.get (curr);
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ptr_vector<pred_transformer> child_pts;
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// get justifying rule and child facts for the derivation of reach_fact at pt
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r = &reach_fact->get_rule ();
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const reach_fact_ref_vector &child_reach_facts =
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reach_fact->get_justifications ();
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// get child pts
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preds.reset();
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pt->find_predecessors(*r, preds);
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for (unsigned j = 0; j < preds.size (); j++) {
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child_pts.push_back (&(get_pred_transformer (preds[j])));
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}
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// update the queues
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reach_facts.append (child_reach_facts);
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pts.append (child_pts);
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// update cex and cex_facts by making a local sat check:
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// check consistency of reach facts of children, rule body, and cex_fact
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cex_ctx->push ();
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cex_ctx->assert_expr (cex_fact);
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unsigned u_tail_sz = r->get_uninterpreted_tail_size ();
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SASSERT (child_reach_facts.size () == u_tail_sz);
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for (unsigned i = 0; i < u_tail_sz; i++) {
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expr_ref ofml (m);
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m_pm.formula_n2o(child_reach_facts[i]->get(), ofml, i);
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cex_ctx->assert_expr (ofml);
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}
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cex_ctx->assert_expr(pt->transition());
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cex_ctx->assert_expr(pt->rule2tag(r));
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TRACE("cex", cex_ctx->display(tout););
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lbool res = cex_ctx->check_sat(0, nullptr);
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CTRACE("cex", res == l_false,
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tout << "Cex fact: " << mk_pp(cex_fact, m) << "\n";
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for (unsigned i = 0; i < u_tail_sz; i++)
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tout << "Pre" << i << " "
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<< mk_pp(child_reach_facts[i]->get(), m) << "\n";
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tout << "Rule: ";
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get_datalog_context().get_rule_manager().display_smt2(*r, tout) << "\n";
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);
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VERIFY (res == l_true);
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model_ref local_mdl;
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cex_ctx->get_model (local_mdl);
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cex_ctx->pop (1);
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local_mdl->set_model_completion(true);
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if (first) {
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unsigned sig_size = pt->sig_size();
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expr_ref_vector ground_fact_conjs(m);
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expr_ref_vector ground_arg_vals(m);
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for (unsigned j = 0; j < sig_size; j++) {
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expr_ref sig_arg(m), sig_val(m);
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sig_arg = m.mk_const (m_pm.o2n(pt->sig(j), 0));
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sig_val = (*local_mdl)(sig_arg);
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ground_arg_vals.push_back(sig_val);
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}
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cex.push_back(m.mk_app(pt->head(), sig_size, ground_arg_vals.c_ptr()));
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first = false;
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}
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for (unsigned i = 0; i < child_pts.size(); i++) {
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pred_transformer& ch_pt = *(child_pts.get(i));
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unsigned sig_size = ch_pt.sig_size();
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expr_ref_vector ground_fact_conjs(m);
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expr_ref_vector ground_arg_vals(m);
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for (unsigned j = 0; j < sig_size; j++) {
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expr_ref sig_arg(m), sig_val(m);
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sig_arg = m.mk_const (m_pm.o2o(ch_pt.sig(j), 0, i));
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sig_val = (*local_mdl)(sig_arg);
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ground_fact_conjs.push_back(m.mk_eq(sig_arg, sig_val));
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ground_arg_vals.push_back(sig_val);
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}
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if (!ground_fact_conjs.empty()) {
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expr_ref ground_fact(m);
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ground_fact = mk_and(ground_fact_conjs);
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m_pm.formula_o2n(ground_fact, ground_fact, i);
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cex_facts.push_back (ground_fact);
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} else {
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cex_facts.push_back (m.mk_true ());
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}
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cex.push_back(m.mk_app(ch_pt.head(),
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sig_size, ground_arg_vals.c_ptr()));
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premises.reset();
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conclusion.reset();
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positions.reset();
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substs.reset();
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}
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SASSERT(!pf || !m.is_hyper_resolve(pf));
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if (pf) {
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cex.push_back(m.get_fact(pf));
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}
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TRACE ("spacer", tout << "ground cex\n" << cex << "\n";);
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@ -3091,7 +2994,7 @@ expr_ref context::get_ground_sat_answer() {
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return mk_and(cex);
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}
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void context::display_certificate(std::ostream &out) {
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void context::display_certificate(std::ostream &out) const {
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switch(m_last_result) {
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case l_false:
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out << mk_pp(mk_unsat_answer(), m);
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@ -1006,7 +1006,7 @@ class context {
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/**
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\brief Retrieve satisfying assignment with explanation.
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*/
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expr_ref mk_sat_answer() {return get_ground_sat_answer();}
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expr_ref mk_sat_answer() const {return get_ground_sat_answer();}
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expr_ref mk_unsat_answer() const;
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unsigned get_cex_depth ();
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@ -1065,6 +1065,7 @@ public:
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ast_manager& get_ast_manager() const {return m;}
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manager& get_manager() {return m_pm;}
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const manager & get_manager() const {return m_pm;}
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decl2rel const& get_pred_transformers() const {return m_rels;}
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pred_transformer& get_pred_transformer(func_decl* p) const {return *m_rels.find(p);}
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@ -1082,8 +1083,8 @@ public:
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* get bottom-up (from query) sequence of ground predicate instances
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* (for e.g. P(0,1,0,0,3)) that together form a ground derivation to query
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*/
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expr_ref get_ground_sat_answer ();
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proof_ref get_ground_refutation();
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expr_ref get_ground_sat_answer () const;
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proof_ref get_ground_refutation() const;
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void get_rules_along_trace (datalog::rule_ref_vector& rules);
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void collect_statistics(statistics& st) const;
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@ -1091,7 +1092,7 @@ public:
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void reset();
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std::ostream& display(std::ostream& out) const;
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void display_certificate(std::ostream& out);
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void display_certificate(std::ostream& out) const;
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pob& get_root() const {return m_pob_queue.get_root();}
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void set_query(func_decl* q) {m_query_pred = q;}
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@ -1,7 +1,7 @@
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#include "muz/spacer/spacer_sat_answer.h"
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#include "muz/base/dl_context.h"
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#include "muz/base/dl_rule.h"
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#include "ast/scoped_proof.h"
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#include "smt/smt_solver.h"
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namespace spacer {
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@ -44,15 +44,16 @@ struct ground_sat_answer_op::frame {
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pred_transformer &pt() {return m_pt;}
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};
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ground_sat_answer_op::ground_sat_answer_op(context &ctx) :
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ground_sat_answer_op::ground_sat_answer_op(const context &ctx) :
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m_ctx(ctx), m(m_ctx.get_ast_manager()), m_pm(m_ctx.get_manager()),
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m_pinned(m) {
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m_solver = mk_smt_solver(m, params_ref::get_empty(), symbol::null);
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}
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proof_ref ground_sat_answer_op::operator()(pred_transformer &query) {
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// -- turn on proof mode so that proof constructing API in ast_manager work correctly
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scoped_proof _pf(m);
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m_solver = mk_smt_solver(m, params_ref::get_empty(), symbol::null);
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vector<frame> todo, new_todo;
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// -- find substitution for a query if query is not nullary
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@ -29,9 +29,9 @@ Revision History:
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namespace spacer {
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class ground_sat_answer_op {
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context &m_ctx;
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const context &m_ctx;
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ast_manager &m;
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manager &m_pm;
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const manager &m_pm;
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expr_ref_vector m_pinned;
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obj_map<expr, proof*> m_cache;
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@ -46,7 +46,7 @@ class ground_sat_answer_op {
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model_ref &mdl, expr_ref_vector &subst);
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public:
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ground_sat_answer_op(context &ctx);
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ground_sat_answer_op(const context &ctx);
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proof_ref operator() (pred_transformer &query);
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};
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