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Merge remote-tracking branch 'Z3Prover/polysat' into polysat

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This commit is contained in:
Clemens Eisenhofer 2022-12-25 12:41:39 +01:00
commit 74ec28201e
41 changed files with 2206 additions and 661 deletions
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133
src/math/polysat/solver.cpp
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@ -53,6 +53,7 @@ namespace polysat {
m_config.m_max_conflicts = m_params.get_uint("max_conflicts", UINT_MAX);
m_config.m_max_decisions = m_params.get_uint("max_decisions", UINT_MAX);
m_config.m_log_conflicts = pp.log_conflicts();
m_rand.set_seed(m_params.get_uint("random_seed", 0));
}
bool solver::should_search() {
@ -75,6 +76,7 @@ namespace polysat {
LOG("Assignment: " << assignments_pp(*this));
if (is_conflict()) LOG("Conflict: " << m_conflict);
IF_LOGGING(m_viable.log());
SASSERT(var_queue_invariant());
if (is_conflict() && at_base_level()) { LOG_H2("UNSAT"); return l_false; }
else if (is_conflict()) resolve_conflict();
else if (should_add_pwatch()) add_pwatch();
@ -241,9 +243,11 @@ namespace polysat {
for (; i < sz && !is_conflict(); ++i)
if (!propagate(v, wlist[i]))
wlist[j++] = wlist[i];
for (; i < sz; ++i)
for (; i < sz; ++i)
wlist[j++] = wlist[i];
wlist.shrink(j);
if (is_conflict())
shuffle(wlist.size(), wlist.data(), m_rand);
DEBUG_CODE(m_locked_wlist = std::nullopt;);
}
@ -394,7 +398,7 @@ namespace polysat {
void solver::add_pwatch(constraint* c, pvar v) {
SASSERT(m_locked_wlist != v); // the propagate loop will not discover the new size
LOG_V("Watching v" << v << " in constraint " << show_deref(c));
LOG_V(20, "Watching v" << v << " in constraint " << show_deref(c));
m_pwatch[v].push_back(c);
}
@ -495,7 +499,7 @@ namespace polysat {
}
case trail_instr_t::assign_i: {
auto v = m_search.back().var();
LOG_V("Undo assign_i: v" << v);
LOG_V(20, "Undo assign_i: v" << v);
unsigned active_level = get_level(v);
if (active_level <= target_level) {
@ -511,7 +515,7 @@ namespace polysat {
}
case trail_instr_t::assign_bool_i: {
sat::literal lit = m_search.back().lit();
LOG_V("Undo assign_bool_i: " << lit);
LOG_V(20, "Undo assign_bool_i: " << lit);
unsigned active_level = m_bvars.level(lit);
if (active_level <= target_level)
@ -588,15 +592,13 @@ namespace polysat {
// Simple hack to try deciding the boolean skeleton first
if (!can_bdecide()) {
// enqueue all not-yet-true clauses
for (auto const& cls : m_constraints.clauses()) {
for (auto const& cl : cls) {
bool is_true = any_of(*cl, [&](sat::literal lit) { return m_bvars.is_true(lit); });
if (is_true)
continue;
size_t undefs = count_if(*cl, [&](sat::literal lit) { return !m_bvars.is_assigned(lit); });
if (undefs >= 2)
m_lemmas.push_back(cl.get());
}
for (clause const& cl : m_constraints.clauses()) {
bool is_true = any_of(cl, [&](sat::literal lit) { return m_bvars.is_true(lit); });
if (is_true)
continue;
size_t undefs = count_if(cl, [&](sat::literal lit) { return !m_bvars.is_assigned(lit); });
if (undefs >= 2)
m_lemmas.push_back(&cl);
}
}
#endif
@ -608,7 +610,7 @@ namespace polysat {
}
void solver::bdecide() {
clause& lemma = *m_lemmas[m_lemmas_qhead++];
clause const& lemma = *m_lemmas[m_lemmas_qhead++];
on_scope_exit update_trail = [this]() {
// must be done after push_level, but also if we return early.
m_trail.push_back(trail_instr_t::lemma_qhead_i);
@ -654,7 +656,7 @@ namespace polysat {
// (fail here in debug mode so we notice if we miss some)
DEBUG_CODE( UNREACHABLE(); );
m_free_pvars.unassign_var_eh(v);
set_conflict(v, false);
SASSERT(is_conflict());
return;
case find_t::singleton:
// NOTE: this case may happen legitimately if all other possibilities were excluded by brute force search
@ -734,9 +736,16 @@ namespace polysat {
SASSERT(!m_search.assignment().contains(v));
if (lemma) {
add_clause(*lemma);
SASSERT(!is_conflict()); // if we have a conflict here, we could have produced this lemma already earlier
if (can_propagate())
if (is_conflict()) {
// If we have a conflict here, we should have produced this lemma already earlier
LOG("Conflict after constraint::produce_lemma: TODO: should have found this lemma earlier");
m_free_pvars.unassign_var_eh(v);
return;
}
if (can_propagate()) {
m_free_pvars.unassign_var_eh(v);
return;
}
}
if (c) {
LOG_H2("Chosen assignment " << assignment_pp(*this, v, val) << " is not actually viable!");
@ -753,10 +762,11 @@ namespace polysat {
case find_t::empty:
LOG("Fallback solver: unsat");
m_free_pvars.unassign_var_eh(v);
set_conflict(v, true);
SASSERT(is_conflict());
return;
case find_t::resource_out:
UNREACHABLE(); // TODO: abort solving
m_free_pvars.unassign_var_eh(v);
return;
}
}
@ -938,7 +948,6 @@ namespace polysat {
clause* best_lemma = nullptr;
auto appraise_lemma = [&](clause* lemma) {
m_simplify_clause.apply(*lemma);
auto score = compute_lemma_score(*lemma);
if (score)
LOG(" score: " << *score);
@ -958,14 +967,14 @@ namespace polysat {
appraise_lemma(lemmas.back());
}
SASSERT(best_score < lemma_score::max());
SASSERT(best_lemma);
VERIFY(best_lemma);
unsigned const jump_level = std::max(best_score.jump_level(), base_level());
SASSERT(jump_level <= max_jump_level);
LOG("best_score: " << best_score);
LOG("best_lemma: " << *best_lemma);
m_conflict.reset();
backjump(jump_level);
@ -1054,7 +1063,11 @@ namespace polysat {
void solver::assign_eval(sat::literal lit) {
signed_constraint const c = lit2cnstr(lit);
LOG_V(10, "Evaluate: " << lit_pp(*this ,lit));
// assertion is false
if (!c.is_currently_true(*this)) IF_VERBOSE(0, verbose_stream() << c << " is not currently true\n");
SASSERT(c.is_currently_true(*this));
VERIFY(c.is_currently_true(*this));
unsigned level = 0;
// NOTE: constraint may be evaluated even if some variables are still unassigned (e.g., 0*x doesn't depend on x).
for (auto v : c->vars())
@ -1309,12 +1322,10 @@ namespace polysat {
for (auto c : m_constraints)
out << "\t" << c->bvar2string() << ": " << *c << "\n";
out << "Clauses:\n";
for (auto const& cls : m_constraints.clauses()) {
for (auto const& cl : cls) {
out << "\t" << *cl << "\n";
for (auto lit : *cl)
out << "\t\t" << lit << ": " << lit2cnstr(lit) << "\n";
}
for (clause const& cl : m_constraints.clauses()) {
out << "\t" << cl << "\n";
for (sat::literal lit : cl)
out << "\t\t" << lit << ": " << lit2cnstr(lit) << "\n";
}
return out;
}
@ -1430,23 +1441,20 @@ namespace polysat {
// Check for missed boolean propagations:
// - no clause should have exactly one unassigned literal, unless it is already true.
// - no clause should be false
for (auto const& cls : m_constraints.clauses()) {
for (auto const& clref : cls) {
clause const& cl = *clref;
bool const is_true = any_of(cl, [&](auto lit) { return m_bvars.is_true(lit); });
if (is_true)
continue;
size_t const undefs = count_if(cl, [&](auto lit) { return !m_bvars.is_assigned(lit); });
if (undefs == 1) {
LOG("Missed boolean propagation of clause: " << cl);
for (sat::literal lit : cl) {
LOG(" " << lit_pp(*this, lit));
}
for (clause const& cl : m_constraints.clauses()) {
bool const is_true = any_of(cl, [&](auto lit) { return m_bvars.is_true(lit); });
if (is_true)
continue;
size_t const undefs = count_if(cl, [&](auto lit) { return !m_bvars.is_assigned(lit); });
if (undefs == 1) {
LOG("Missed boolean propagation of clause: " << cl);
for (sat::literal lit : cl) {
LOG(" " << lit_pp(*this, lit));
}
SASSERT(undefs != 1);
bool const is_false = all_of(cl, [&](auto lit) { return m_bvars.is_false(lit); });
SASSERT(!is_false);
}
SASSERT(undefs != 1);
bool const is_false = all_of(cl, [&](auto lit) { return m_bvars.is_false(lit); });
SASSERT(!is_false);
}
return true;
}
@ -1456,7 +1464,7 @@ namespace polysat {
}
/** Check that boolean assignment and constraint evaluation are consistent */
bool solver::assignment_invariant() {
bool solver::assignment_invariant() const {
if (is_conflict())
return true;
bool ok = true;
@ -1475,6 +1483,25 @@ namespace polysat {
return ok;
}
/** Check that each variable is either assigned or queued for decisions */
bool solver::var_queue_invariant() const {
if (is_conflict())
return true;
uint_set active;
for (pvar v : m_free_pvars)
active.insert(v);
for (auto const& [v, val] : assignment())
active.insert(v);
bool ok = true;
for (pvar v = 0; v < num_vars(); ++v) {
if (!active.contains(v)) {
ok = false;
LOG("Lost variable v" << v << " (it is neither assigned nor free)");
}
}
return ok;
}
/// Check that all constraints on the stack are satisfied by the current model.
bool solver::verify_sat() {
LOG_H1("Checking current model...");
@ -1487,19 +1514,17 @@ namespace polysat {
all_ok = all_ok && ok;
}
}
for (auto clauses : m_constraints.clauses()) {
for (auto cl : clauses) {
bool clause_ok = false;
for (sat::literal lit : *cl) {
bool ok = lit2cnstr(lit).is_currently_true(*this);
if (ok) {
clause_ok = true;
break;
}
for (clause const& cl : m_constraints.clauses()) {
bool clause_ok = false;
for (sat::literal lit : cl) {
bool ok = lit2cnstr(lit).is_currently_true(*this);
if (ok) {
clause_ok = true;
break;
}
LOG((clause_ok ? "PASS" : "FAIL") << ": " << show_deref(cl) << (cl->is_redundant() ? " (redundant)" : ""));
all_ok = all_ok && clause_ok;
}
LOG((clause_ok ? "PASS" : "FAIL") << ": " << cl << (cl.is_redundant() ? " (redundant)" : ""));
all_ok = all_ok && clause_ok;
}
if (all_ok) LOG("All good!");
return all_ok;