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Merge branch 'polysat' of https://github.com/z3prover/z3 into polysat

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This commit is contained in:
Nikolaj Bjorner 2021-09-13 16:49:45 +02:00
commit 9e6fd7cb70
9 changed files with 107 additions and 97 deletions
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57
src/math/polysat/conflict_core.cpp
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@ -50,12 +50,12 @@ namespace polysat {
std::ostream& conflict_core::display(std::ostream& out) const {
char const* sep = "";
for (auto c : m_constraints)
for (auto c : *this)
out << sep << c, sep = " ; ";
if (!m_vars.empty())
out << " vars";
for (auto v : m_vars)
out << " " << v;
out << " v" << v;
return out;
}
@ -136,14 +136,29 @@ namespace polysat {
}
void conflict_core::remove_var(pvar v) {
LOG("Removing v" << v << " from core");
unsigned j = 0;
for (unsigned i = 0; i < m_constraints.size(); ++i)
if (m_constraints[i]->contains_var(v))
unset_mark(m_constraints[i]);
else
m_constraints[j++] = m_constraints[i];
m_constraints[j++] = m_constraints[i];
m_constraints.shrink(j);
indexed_uint_set literals_copy = m_literals; // TODO: can avoid copy (e.g., add a filter method for indexed_uint_set)
for (unsigned lit_idx : literals_copy) {
signed_constraint c = cm().lookup(sat::to_literal(lit_idx));
if (c->contains_var(v)) {
unset_mark(c);
m_literals.remove(lit_idx);
}
}
m_vars.remove(v);
}
void conflict_core::set_bailout() {
SASSERT(!is_bailout());
m_bailout = true;
s().m_stats.m_num_bailouts++;
}
void conflict_core::resolve(constraint_manager const& m, sat::bool_var var, clause const& cl) {
@ -152,9 +167,10 @@ namespace polysat {
// resolvent: ~y \/ ~z \/ u \/ v; as core: y, z, ~u, ~v
SASSERT(var != sat::null_bool_var);
SASSERT(std::all_of(m_constraints.begin(), m_constraints.end(), [](auto c){ return !c->has_bvar(); }));
bool core_has_pos = contains_literal(sat::literal(var));
bool core_has_neg = contains_literal(~sat::literal(var));
DEBUG_CODE({
bool core_has_pos = std::count_if(begin(), end(), [var](auto c){ return c.blit() == sat::literal(var); }) > 0;
bool core_has_neg = std::count_if(begin(), end(), [var](auto c){ return c.blit() == ~sat::literal(var); }) > 0;
bool clause_has_pos = std::count(cl.begin(), cl.end(), sat::literal(var)) > 0;
bool clause_has_neg = std::count(cl.begin(), cl.end(), ~sat::literal(var)) > 0;
SASSERT(!core_has_pos || !core_has_neg); // otherwise core is tautology
@ -162,14 +178,10 @@ namespace polysat {
SASSERT((core_has_pos && clause_has_pos) || (core_has_neg && clause_has_neg));
});
int j = 0;
for (auto c : m_constraints) {
if (c->bvar() != var)
m_constraints[j++] = c;
else
unset_mark(c);
}
m_constraints.shrink(j);
if (core_has_pos)
remove_literal(sat::literal(var));
if (core_has_neg)
remove_literal(~sat::literal(var));
for (sat::literal lit : cl)
if (lit.var() != var)
@ -179,9 +191,9 @@ namespace polysat {
/** If the constraint c is a temporary constraint derived by core saturation, insert it (and recursively, its premises) into \Gamma */
void conflict_core::keep(signed_constraint c) {
if (!c->has_bvar()) {
m_constraints.erase(c);
remove(c);
cm().ensure_bvar(c.get());
insert_literal(c.blit());
insert(c);
}
LOG_H3("keeping: " << c);
// NOTE: maybe we should skip intermediate steps and just collect the leaf premises for c?
@ -194,6 +206,7 @@ namespace polysat {
for (auto premise : premises) {
keep(premise);
SASSERT(premise->has_bvar());
SASSERT(s().m_bvars.value(premise.blit()) == l_true); // otherwise the propagation doesn't make sense
c_lemma.push(~premise.blit());
active_level = std::max(active_level, s().m_bvars.level(premise.blit()));
}
@ -210,11 +223,13 @@ namespace polysat {
clause_builder lemma(s());
for (auto c : m_constraints) {
if (!c->has_bvar())
keep(c);
lemma.push(~c);
SASSERT(!c->has_bvar());
keep(c);
}
for (auto c : *this)
lemma.push(~c);
for (unsigned v : m_vars) {
if (!is_pmarked(v))
continue;
@ -355,6 +370,10 @@ namespace polysat {
return m_bvar2mark.get(b, false);
}
bool conflict_core::contains_literal(sat::literal lit) const {
return m_literals.contains(lit.to_uint());
}
void conflict_core::insert_literal(sat::literal lit) {
m_literals.insert(lit.to_uint());
}