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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 2021-10-06 13:01:29 -07:00
commit 5ee5197ea9
3 changed files with 31 additions and 16 deletions
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3
src/math/polysat/conflict.cpp
View file

@ -125,7 +125,6 @@ namespace polysat {
* should appear, otherwise the lemma would be a tautology
*/
void conflict::insert(signed_constraint c) {
if (c.is_always_true())
return;
if (c->is_marked())
@ -321,7 +320,7 @@ namespace polysat {
bool conflict::try_eliminate(pvar v) {
bool has_v = false;
for (auto c : *this)
has_v |= c->contains_var(v);
has_v |= c->is_var_dependent() && c->contains_var(v);
if (!has_v)
return true;
for (auto* engine : ve_engines)

9
src/math/polysat/saturation.cpp
View file

@ -78,11 +78,14 @@ namespace polysat {
if (!c.is_currently_false(s))
return false;
core.replace(crit1, c, new_constraints);
core.reset();
core.set(c);
for (auto d : new_constraints)
core.insert(d);
c->set_var_dependent();
core.insert(~c);
return true;
}
bool inf_saturate::propagate(conflict& core, inequality const& crit1, inequality const& crit2, bool is_strict, pdd const& lhs, pdd const& rhs, vector<signed_constraint>& new_constraints) {

35
src/math/polysat/solver.cpp
View file

@ -122,16 +122,13 @@ namespace polysat {
m_constraints.ensure_bvar(c.get());
sat::literal lit = c.blit();
LOG("New constraint: " << c);
if (m_bvars.is_false(lit)) {
set_conflict(c /*, dep*/);
if (m_bvars.is_false(lit) || c.is_currently_false(*this)) {
set_conflict(c /*, dep */);
return;
}
m_bvars.assign(lit, m_level, nullptr, nullptr, dep);
m_trail.push_back(trail_instr_t::assign_bool_i);
m_search.push_boolean(lit);
if (c.is_currently_false(*this))
set_conflict(c /*, dep */);
#if ENABLE_LINEAR_SOLVER
m_linear_solver.new_constraint(*c.get());
@ -200,13 +197,13 @@ namespace polysat {
if (m_bvars.is_true(cl[idx]))
return false;
unsigned i = 2;
for (; i < cl.size() && (m_bvars.is_false(cl[i]) || lit2cnstr(cl[i]).is_currently_false(*this)); ++i);
for (; i < cl.size() && m_bvars.is_false(cl[i]); ++i);
if (i < cl.size()) {
m_bvars.watch(cl[i]).push_back(&cl);
std::swap(cl[1 - idx], cl[i]);
return true;
}
if (m_bvars.is_false(cl[idx]) || lit2cnstr(cl[idx]).is_currently_false(*this))
if (m_bvars.is_false(cl[idx]))
set_conflict(cl);
else
assign_bool(level(cl), cl[idx], &cl, nullptr);
@ -526,8 +523,6 @@ namespace polysat {
// Guess a literal from the given clause; returns the guessed constraint
void solver::decide_bool(clause& lemma) {
if (is_conflict())
return;
LOG_H3("Guessing literal in lemma: " << lemma);
IF_LOGGING(m_viable.log());
LOG("Boolean assignment: " << m_bvars);
@ -625,8 +620,24 @@ namespace polysat {
// (L')^{L' \/ ¬L \/ ...}
// again L is in core, unless we core-reduced it away
clause_builder reason_builder = m_conflict.build_lemma();
SASSERT(std::find(reason_builder.begin(), reason_builder.end(), ~lit));
clause_builder reason_builder = m_conflict.build_lemma();
bool contains_lit = std::find(reason_builder.begin(), reason_builder.end(), ~lit);
if (!contains_lit) {
// At this point, we do not have ~lit in the reason.
// For now, we simply add it (thus weakening the reason)
//
// Alternative (to be considered later):
// - 'reason' itself (without ~L) would already be an explanation for ~L
// - however if it doesn't contain ~L, it breaks the boolean resolution invariant
// - would need to check what we can gain by relaxing that invariant
// - drawback: might have to bail out at boolean resolution
// Also: maybe we can skip ~L in some cases? but in that case it shouldn't be marked.
//
std::cout << "ADD extra " << ~lit << "\n";
reason_builder.push(~lit);
}
clause_ref reason = reason_builder.build();
if (reason->empty()) {
@ -856,6 +867,8 @@ namespace polysat {
signed_constraint sc(c, is_positive);
for (auto const& wlist : m_pwatch) {
auto n = std::count(wlist.begin(), wlist.end(), sc);
if (n > 1)
std::cout << sc << "\n" << * this << "\n";
VERIFY(n <= 1); // no duplicates in the watchlist
num_watches += n;
}