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https://github.com/Z3Prover/z3
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v2 of dual maxres engine
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
622d8b5cd1
commit
d429e72e92
6 changed files with 253 additions and 139 deletions
166
src/opt/mss.cpp
166
src/opt/mss.cpp
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@ -27,35 +27,74 @@ Notes:
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namespace opt {
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mss::mss(solver& s, ast_manager& m): s(s), m(m), m_cancel(false) {
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mss::mss(ref<solver>& s, ast_manager& m): m_s(s), m(m), m_cancel(false) {
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}
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mss::~mss() {
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}
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}
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void mss::check_parameters(vector<exprs > const& cores, exprs& literals) {
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bool mss::check_result() {
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lbool is_sat = m_s->check_sat(m_mss.size(), m_mss.c_ptr());
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if (is_sat == l_undef) return true;
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SASSERT(is_sat == l_true);
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if (is_sat == l_false) return false;
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expr_set::iterator it = m_mcs.begin(), end = m_mcs.end();
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for (; it != end; ++it) {
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m_mss.push_back(*it);
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is_sat = m_s->check_sat(m_mss.size(), m_mss.c_ptr());
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m_mss.pop_back();
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if (is_sat == l_undef) return true;
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SASSERT(is_sat == l_false);
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if (is_sat == l_true) return false;
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}
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return true;
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}
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void mss::initialize(vector<exprs>& cores, exprs& literals) {
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expr* n;
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expr_set lits, core_lits;
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for (unsigned i = 0; i < literals.size(); ++i) {
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n = literals[i];
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lits.insert(n);
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m.is_not(n, n);
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if (!is_uninterp_const(n)) {
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throw default_exception("arguments have to be uninterpreted literals");
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}
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}
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// cores are disjoint
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// cores are a subset of literals
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// literals not in cores evaluate to true in current model
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}
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/**
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\brief Move literals satisfied in todo into mss.
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Precondition: the solver state is satisfiable.
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*/
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void mss::update_model() {
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exprs rest_core;
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expr_ref tmp(m);
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s.get_model(m_model);
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update_set(m_todo);
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//
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// the last core is a dummy core. It contains literals that
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// did not occur in previous cores and did not evaluate to true
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// in the current model.
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//
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for (unsigned i = 0; i < cores.size(); ++i) {
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exprs const& core = cores[i];
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for (unsigned j = 0; j < core.size(); ++j) {
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expr* n = core[j];
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if (!core_lits.contains(n)) {
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core_lits.insert(n);
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VERIFY(m_model->eval(n, tmp));
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if (m.is_true(tmp)) {
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m_mss.push_back(n);
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}
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}
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}
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}
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for (unsigned i = 0; i < literals.size(); ++i) {
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expr* n = literals[i];
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if (!core_lits.contains(n)) {
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VERIFY(m_model->eval(n, tmp));
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if (m.is_true(tmp)) {
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m_mss.push_back(n);
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}
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else {
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rest_core.push_back(n);
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core_lits.insert(n);
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}
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}
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}
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cores.push_back(rest_core);
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}
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void mss::update_set(exprs& lits) {
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@ -69,7 +108,7 @@ namespace opt {
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continue;
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}
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VERIFY(m_model->eval(n, tmp));
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if (m.is_false(tmp)) {
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if (!m.is_true(tmp)) {
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if (j != i) {
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lits[j] = lits[i];
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}
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@ -83,33 +122,44 @@ namespace opt {
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}
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lbool mss::operator()(vector<exprs> const& cores, exprs& literals) {
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lbool mss::operator()(vector<exprs> const& _cores, exprs& literals) {
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m_mss.reset();
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m_mcs.reset();
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m_todo.reset();
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m_todo.append(literals);
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check_parameters(cores, literals);
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update_model();
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m_s->get_model(m_model);
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SASSERT(m_model);
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vector<exprs> cores(_cores);
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TRACE("opt",
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for (unsigned i = 0; i < cores.size(); ++i) {
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display_vec(tout << "core: ", cores[i].size(), cores[i].c_ptr());
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}
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display_vec(tout << "lits: ", literals.size(), literals.c_ptr());
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);
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initialize(cores, literals);
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TRACE("opt", display(tout););
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lbool is_sat = l_true;
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for (unsigned i = 0; is_sat == l_true && i < cores.size(); ++i) {
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is_sat = process_core(cores[i]);
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bool has_mcs = false;
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bool is_last = i + 1 < cores.size();
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SASSERT(check_invariant());
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update_set(cores[i]);
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is_sat = process_core(1, cores[i], has_mcs, is_last);
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}
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if (is_sat == l_true) {
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SASSERT(check_invariant());
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TRACE("opt", display(tout););
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literals.reset();
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literals.append(m_mss);
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SASSERT(check_result());
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}
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return is_sat;
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}
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lbool mss::process_core(exprs const& _core) {
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// at least one literal in core is false in current model.
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// pick literals in core that are not yet in mss.
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exprs core(_core);
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update_set(core);
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return process_core(1, core);
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}
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lbool mss::process_core(unsigned sz, exprs& core) {
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//
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// at least one literal in core is false in current model.
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// pick literals in core that are not yet in mss.
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//
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lbool mss::process_core(unsigned sz, exprs& core, bool& has_mcs, bool is_last) {
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TRACE("opt", tout << "process: " << sz << " out of " << core.size() << " literals\n";);
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SASSERT(sz > 0);
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if (core.empty()) {
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@ -118,18 +168,25 @@ namespace opt {
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if (m_cancel) {
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return l_undef;
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}
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if (sz == 1 && is_last && !has_mcs) {
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// there has to be at least one false
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// literal in the core.
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m_mcs.insert(core[0]);
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return l_true;
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}
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sz = std::min(sz, core.size());
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unsigned sz_save = m_mss.size();
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m_mss.append(sz, core.c_ptr());
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lbool is_sat = s.check_sat(m_mss.size(), m_mss.c_ptr());
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lbool is_sat = m_s->check_sat(m_mss.size(), m_mss.c_ptr());
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m_mss.resize(sz_save);
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switch (is_sat) {
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case l_true:
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update_model();
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m_s->get_model(m_model);
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update_set(core);
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return process_core(2*sz, core);
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return process_core(2*sz, core, has_mcs, is_last);
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case l_false:
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if (sz == 1) {
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has_mcs = true;
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m_mcs.insert(core[0]);
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core[0] = core.back();
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core.pop_back();
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@ -138,12 +195,12 @@ namespace opt {
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exprs core2;
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core2.append(core.size()-sz, core.c_ptr()+sz);
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core.resize(sz);
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is_sat = process_core(sz, core2);
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is_sat = process_core(sz, core2, has_mcs, false);
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if (is_sat != l_true) {
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return is_sat;
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}
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}
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return process_core(1, core);
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return process_core(1, core, has_mcs, is_last);
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case l_undef:
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return l_undef;
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}
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@ -151,8 +208,41 @@ namespace opt {
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return l_true;
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}
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void mss::display_vec(std::ostream& out, unsigned sz, expr* const* args) const {
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for (unsigned i = 0; i < sz; ++i) {
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out << mk_pp(args[i], m) << " ";
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}
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out << "\n";
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}
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void mss::display(std::ostream& out) const {
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expr_set::iterator it = m_mcs.begin(), end = m_mcs.end();
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out << "mcs:\n";
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for (; it != end; ++it) {
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out << mk_pp(*it, m) << "\n";
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}
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out << "\n";
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out << "mss:\n";
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for (unsigned i = 0; i < m_mss.size(); ++i) {
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out << mk_pp(m_mss[i], m) << "\n";
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}
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out << "\n";
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if (m_model) {
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model_smt2_pp(out, m, *(m_model.get()), 0);
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}
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}
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bool mss::check_invariant() const {
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if (!m_model) return true;
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expr_ref tmp(m);
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for (unsigned i = 0; i < m_mss.size(); ++i) {
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expr* n = m_mss[i];
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VERIFY(m_model->eval(n, tmp));
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CTRACE("opt", !m.is_true(tmp), tout << mk_pp(n, m) << " |-> " << mk_pp(tmp, m) << "\n";);
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SASSERT(!m.is_false(tmp));
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}
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return true;
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}
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}
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