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https://github.com/Z3Prover/z3
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update polynomial superposition
This commit is contained in:
Jakob Rath
parent
2de443c74f
commit
ba8fa1f072
5 changed files with 60 additions and 85 deletions
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@ -30,10 +30,10 @@ namespace polysat {
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unsigned_vector m_marks;
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unsigned m_clock { 0 };
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public:
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// allocated size (not the number of active variables)
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unsigned size() const { return m_level.size(); }
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public:
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sat::bool_var new_var();
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void del_var(sat::bool_var var);
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@ -25,9 +25,12 @@ namespace polysat {
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conflict_core::conflict_core(solver& s) {
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m_solver = &s;
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ex_engines.push_back(alloc(ex_polynomial_superposition));
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for (auto* engine : ex_engines)
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engine->set_solver(s);
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ve_engines.push_back(alloc(ve_reduction));
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// ve_engines.push_back(alloc(ve_forbidden_intervals));
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inf_engines.push_back(alloc(inf_polynomial_superposition));
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// inf_engines.push_back(alloc(inf_polynomial_superposition));
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for (auto* engine : inf_engines)
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engine->set_solver(s);
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}
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@ -245,6 +248,10 @@ namespace polysat {
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for (auto c : cjust_v)
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insert(c);
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for (auto* engine : ex_engines)
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if (engine->try_explain(v, *this))
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return true;
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// No value resolution method was successful => fall back to saturation and variable elimination
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while (true) { // TODO: limit?
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// TODO: as a last resort, substitute v by m_value[v]?
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@ -99,7 +99,7 @@ namespace polysat {
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pdd lhs;
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pdd rhs;
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bool is_strict;
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constraint const* src;
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constraint const* src; // TODO: should be signed_constraint now
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inequality(pdd const & lhs, pdd const & rhs, bool is_strict, constraint const* src):
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lhs(lhs), rhs(rhs), is_strict(is_strict), src(src) {}
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};
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@ -19,108 +19,71 @@ namespace polysat {
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constraint_manager& explainer::cm() { return s().m_constraints; }
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signed_constraint ex_polynomial_superposition::resolve1(pvar v, signed_constraint c1, signed_constraint c2) {
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// c1 is true, c2 is false
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SASSERT(c1.is_currently_true(s()));
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SASSERT(c2.is_currently_false(s()));
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LOG("c1: " << c1);
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LOG("c2: " << c2);
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pdd a = c1->to_eq().p();
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pdd b = c2->to_eq().p();
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pdd r = a;
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if (!a.resolve(v, b, r) && !b.resolve(v, a, r))
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return {};
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unsigned const lvl = std::max(c1->level(), c2->level());
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signed_constraint c = cm().eq(lvl, r);
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LOG("resolved: " << c << " currently false? " << c.is_currently_false(s()));
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if (!c.is_currently_false(s()))
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return {};
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return c;
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}
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bool ex_polynomial_superposition::is_positive_equality_over(pvar v, signed_constraint const& c) {
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return c.is_positive() && c->is_eq() && c->contains_var(v);
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}
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// TODO(later): check superposition into disequality again (see notes)
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bool ex_polynomial_superposition::try_explain(pvar v, /* vector<signed_constraint> const& cjust_v, */ conflict_core& core) {
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// TODO: core saturation premises are from \Gamma (i.e., has_bvar)... but here we further restrict to the core; might need to revise
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// -- especially: should take into account results from previous saturations (they will be in \Gamma, but only if we use the constraint or one of its descendants for the lemma)
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// actually: we want to take one from the current cjust (currently true) and one from the conflict (currently false)
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// TODO: resolve multiple times... a single time might not be enough to eliminate the variable.
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LOG_H3("Trying polynomial superposition...");
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// true = done, false = abort, undef = continue
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lbool ex_polynomial_superposition::try_explain1(pvar v, conflict_core& core) {
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for (auto it1 = core.begin(); it1 != core.end(); ++it1) {
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signed_constraint c1 = *it1;
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if (!c1->has_bvar())
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continue;
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if (!c1.is_positive())
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continue;
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if (!c1->is_eq())
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continue;
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if (!c1->contains_var(v))
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if (!is_positive_equality_over(v, c1))
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continue;
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if (!c1.is_currently_true(s()))
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continue;
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for (auto it2 = core.begin(); it2 != core.end(); ++it2) {
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signed_constraint c2 = *it2;
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if (!c2->has_bvar())
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continue;
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if (!c2.is_positive())
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continue;
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if (!c2->is_eq())
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continue;
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if (!c2->contains_var(v))
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if (!is_positive_equality_over(v, c2))
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continue;
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if (!c2.is_currently_false(s()))
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continue;
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// TODO: separate method for this; then try_explain1 and try_explain* for multi-steps; replace the false constraint in the core.
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// c1 is true, c2 is false
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LOG("c1: " << c1);
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LOG("c2: " << c2);
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pdd a = c1->to_eq().p();
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pdd b = c2->to_eq().p();
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pdd r = a;
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if (!a.resolve(v, b, r) && !b.resolve(v, a, r))
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continue;
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unsigned const lvl = std::max(c1->level(), c2->level());
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signed_constraint c = cm().eq(lvl, r);
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LOG("resolved: " << c << " currently false? " << c.is_currently_false(s()));
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if (!c.is_currently_false(s()))
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signed_constraint c = resolve1(v, c1, c2);
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if (!c)
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continue;
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vector<signed_constraint> premises;
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premises.push_back(c1);
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premises.push_back(c2);
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core.replace(c2, c, std::move(premises));
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if (!c->contains_var(v)) {
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core.reset(); // TODO: doesn't work; this removes the premises as well... / instead: remove the false one.
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core.insert(c, std::move(premises));
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return true;
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} else {
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core.insert(c, std::move(premises));
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}
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core.keep(c);
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core.remove_var(v);
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return l_true;
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} else
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return l_undef;
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}
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}
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return false;
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return l_false;
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}
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// DEBUG_CODE({
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// if (lemma) {
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// LOG("New lemma: " << *lemma);
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// for (auto* c : lemma->new_constraints()) {
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// LOG("New constraint: " << show_deref(c));
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// }
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// // All constraints in the lemma must be false in the conflict state
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// for (auto lit : lemma->literals()) {
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// if (m_solver.m_bvars.value(lit) == l_false)
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// continue;
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// SASSERT(m_solver.m_bvars.value(lit) != l_true);
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// constraint* c = m_solver.m_constraints.lookup(lit.var());
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// SASSERT(c);
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// tmp_assign _t(c, lit);
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// // if (c->is_currently_true(m_solver)) {
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// // LOG("ERROR: constraint is true: " << show_deref(c));
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// // SASSERT(false);
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// // }
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// // SASSERT(!c->is_currently_true(m_solver));
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// // SASSERT(c->is_currently_false(m_solver)); // TODO: pvar v may not have a value at this point...
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// }
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// }
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// else {
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// LOG("No lemma");
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// }
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// });
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// m_var = null_var;
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// m_cjust_v.reset();
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// return lemma;
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// }
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bool ex_polynomial_superposition::try_explain(pvar v, conflict_core& core) {
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LOG_H3("Trying polynomial superposition...");
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lbool result = l_undef;
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while (result == l_undef)
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result = try_explain1(v, core);
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LOG("success? " << result);
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return result;
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}
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}
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@ -35,7 +35,12 @@ namespace polysat {
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};
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class ex_polynomial_superposition : public explainer {
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bool try_explain(pvar v, /* vector<signed_constraint> const& cjust_v, */ conflict_core& core) override;
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private:
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bool is_positive_equality_over(pvar v, signed_constraint const& c);
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signed_constraint resolve1(pvar v, signed_constraint c1, signed_constraint c2);
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lbool try_explain1(pvar v, conflict_core& core);
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public:
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bool try_explain(pvar v, conflict_core& core) override;
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};
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