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https://github.com/Z3Prover/z3
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deal with subtraction that manages to sneak in. Issue #996
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
aceee3fac8
commit
d14f2af5ae
8 changed files with 84 additions and 47 deletions
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@ -3180,7 +3180,7 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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static lbool core_chunking(sat::solver& s, model const& m, sat::bool_var_vector const& vars, sat::literal_vector const& asms, vector<sat::literal_vector>& conseq, unsigned K) {
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sat::literal_vector lambda;
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for (unsigned i = 0; i < vars.size(); i++) {
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lambda.push_back(sat::literal(i, m[vars[i]] == l_false));
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lambda.push_back(sat::literal(vars[i], m[vars[i]] == l_false));
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}
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while (!lambda.empty()) {
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IF_VERBOSE(1, verbose_stream() << "(sat-backbone-core " << lambda.size() << " " << conseq.size() << ")\n";);
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@ -3259,9 +3259,9 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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}
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}
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// is_sat = core_chunking(*this, mdl, vars, asms, conseq, 100);
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is_sat = core_chunking(*this, mdl, vars, asms, conseq, 100);
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is_sat = get_consequences(asms, lits, conseq);
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// is_sat = get_consequences(asms, lits, conseq);
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set_model(mdl);
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return is_sat;
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}
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@ -3371,13 +3371,14 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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propagate(false);
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if (check_inconsistent()) return l_false;
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unsigned num_units = 0, num_iterations = 0;
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extract_fixed_consequences(num_units, assumptions, unfixed_vars, conseq);
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unsigned num_iterations = 0;
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extract_fixed_consequences(unfixed_lits, assumptions, unfixed_vars, conseq);
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update_unfixed_literals(unfixed_lits, unfixed_vars);
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while (!unfixed_lits.empty()) {
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if (scope_lvl() > 1) {
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pop(scope_lvl() - 1);
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}
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propagate(false);
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++num_iterations;
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checkpoint();
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literal_set::iterator it = unfixed_lits.begin(), end = unfixed_lits.end();
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@ -3389,8 +3390,9 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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literal lit = *it;
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if (value(lit) != l_undef) {
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++num_fixed;
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if (value(lit) == l_true && lvl(lit) == 1) {
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VERIFY(extract_fixed_consequences(lit, assumptions, unfixed_vars, conseq));
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if (lvl(lit) <= 1) {
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SASSERT(value(lit) == l_true);
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extract_fixed_consequences(lit, assumptions, unfixed_vars, conseq);
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}
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continue;
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}
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@ -3409,18 +3411,13 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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++num_resolves;
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}
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if (false && scope_lvl() == 1) {
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is_sat = l_undef;
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break;
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}
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}
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if (scope_lvl() == 1) {
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it = unfixed_lits.begin();
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for (; it != end; ++it) {
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literal lit = *it;
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if (value(lit) == l_true) {
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VERIFY(extract_fixed_consequences(lit, assumptions, unfixed_vars, conseq));
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}
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}
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}
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extract_fixed_consequences(unfixed_lits, assumptions, unfixed_vars, conseq);
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if (is_sat == l_true) {
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if (scope_lvl() == 1 && num_resolves > 0) {
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IF_VERBOSE(1, verbose_stream() << "(sat.get-consequences backjump)\n";);
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@ -3431,6 +3428,7 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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if (is_sat == l_undef) {
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restart();
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}
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extract_fixed_consequences(unfixed_lits, assumptions, unfixed_vars, conseq);
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}
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}
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if (is_sat == l_false) {
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@ -3440,7 +3438,6 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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if (is_sat == l_true) {
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delete_unfixed(unfixed_lits, unfixed_vars);
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}
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extract_fixed_consequences(num_units, assumptions, unfixed_vars, conseq);
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update_unfixed_literals(unfixed_lits, unfixed_vars);
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IF_VERBOSE(1, verbose_stream() << "(sat.get-consequences"
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<< " iterations: " << num_iterations
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@ -3492,19 +3489,27 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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SASSERT(!inconsistent());
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unsigned sz = m_trail.size();
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for (unsigned i = start; i < sz && lvl(m_trail[i]) <= 1; ++i) {
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if (!extract_fixed_consequences(m_trail[i], assumptions, unfixed, conseq)) {
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for (i = 0; i < sz && lvl(m_trail[i]) <= 1; ++i) {
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VERIFY(extract_fixed_consequences(m_trail[i], assumptions, unfixed, conseq));
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}
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break;
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}
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extract_fixed_consequences(m_trail[i], assumptions, unfixed, conseq);
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}
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start = sz;
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}
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void solver::extract_fixed_consequences(literal_set const& unfixed_lits, literal_set const& assumptions, bool_var_set& unfixed_vars, vector<literal_vector>& conseq) {
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literal_set::iterator it = unfixed_lits.begin(), end = unfixed_lits.end();
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for (; it != end; ++it) {
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literal lit = *it;
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if (lvl(lit) <= 1) {
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SASSERT(value(lit) == l_true);
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extract_fixed_consequences(lit, assumptions, unfixed_vars, conseq);
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}
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}
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}
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bool solver::check_domain(literal lit, literal lit2) {
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if (!m_antecedents.contains(lit2.var())) {
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SASSERT(value(lit2) == l_true);
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m_todo_antecedents.push_back(lit2);
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TRACE("sat", tout << "todo: " << lit2 << " " << value(lit2) << "\n";);
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return false;
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}
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else {
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@ -3514,16 +3519,17 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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bool solver::extract_assumptions(literal lit, index_set& s) {
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justification js = m_justification[lit.var()];
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TRACE("sat", tout << lit << " " << js << "\n";);
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switch (js.get_kind()) {
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case justification::NONE:
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break;
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case justification::BINARY:
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if (!check_domain(lit, js.get_literal())) return false;
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if (!check_domain(lit, ~js.get_literal())) return false;
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s |= m_antecedents.find(js.get_literal().var());
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break;
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case justification::TERNARY:
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if (!check_domain(lit, js.get_literal1())) return false;
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if (!check_domain(lit, js.get_literal2())) return false;
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if (!check_domain(lit, ~js.get_literal1()) ||
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!check_domain(lit, ~js.get_literal2())) return false;
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s |= m_antecedents.find(js.get_literal1().var());
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s |= m_antecedents.find(js.get_literal2().var());
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break;
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@ -3531,7 +3537,7 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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clause & c = *(m_cls_allocator.get_clause(js.get_clause_offset()));
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for (unsigned i = 0; i < c.size(); ++i) {
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if (c[i] != lit) {
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if (!check_domain(lit, c[i])) return false;
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if (!check_domain(lit, ~c[i])) return false;
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s |= m_antecedents.find(c[i].var());
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}
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}
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@ -3565,7 +3571,7 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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}
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bool solver::extract_fixed_consequences(literal lit, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq) {
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bool solver::extract_fixed_consequences1(literal lit, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq) {
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index_set s;
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if (m_antecedents.contains(lit.var())) {
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return true;
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@ -3574,16 +3580,9 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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s.insert(lit.index());
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}
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else {
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SASSERT(m_todo_antecedents.empty());
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if (!extract_assumptions(lit, s)) {
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SASSERT(!m_todo_antecedents.empty());
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while (!m_todo_antecedents.empty()) {
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index_set s1;
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if (extract_assumptions(m_todo_antecedents.back(), s1)) {
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m_todo_antecedents.pop_back();
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}
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}
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VERIFY (extract_assumptions(lit, s));
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return false;
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}
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add_assumption(lit);
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}
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@ -3601,6 +3600,16 @@ static void back_remove(sat::literal_vector& lits, sat::literal l) {
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return true;
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}
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void solver::extract_fixed_consequences(literal lit, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq) {
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SASSERT(m_todo_antecedents.empty());
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m_todo_antecedents.push_back(lit);
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while (!m_todo_antecedents.empty()) {
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if (extract_fixed_consequences1(m_todo_antecedents.back(), assumptions, unfixed, conseq)) {
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m_todo_antecedents.pop_back();
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}
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}
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}
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void solver::asymmetric_branching() {
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if (scope_lvl() > 0 || inconsistent())
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return;
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@ -498,7 +498,11 @@ namespace sat {
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void extract_fixed_consequences(unsigned& start, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq);
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bool extract_fixed_consequences(literal lit, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq);
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void extract_fixed_consequences(literal_set const& unfixed_lits, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq);
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void extract_fixed_consequences(literal lit, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq);
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bool extract_fixed_consequences1(literal lit, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq);
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void update_unfixed_literals(literal_set& unfixed_lits, bool_var_set& unfixed_vars);
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