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Polysat: forbidden intervals updates (#5230)

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* Pop assign_eh

* Fix scoped_ptr_vector constructors, add detach()

* Need to copy the returned lemma

* Add test

* Basic inequality tests

* Return disjunctive lemma to caller
This commit is contained in:
Jakob Rath 2021-04-30 17:41:50 +02:00 • committed by GitHub
parent d6e41de344
commit 0c4824f194
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GPG key ID: 4AEE18F83AFDEB23
9 changed files with 189 additions and 24 deletions
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52
src/math/polysat/solver.cpp
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@ -102,7 +102,8 @@ namespace polysat {
}
lbool solver::check_sat() {
TRACE("polysat", tout << "check\n";);
LOG("Starting");
m_disjunctive_lemma.reset();
while (m_lim.inc()) {
LOG_H1("Next solving loop iteration");
LOG("Free variables: " << m_free_vars);
@ -114,7 +115,8 @@ namespace polysat {
}
});
if (is_conflict() && at_base_level()) { LOG_H2("UNSAT"); return l_false; }
if (pending_disjunctive_lemma()) { LOG_H2("UNDEF (handle lemma externally)"); return l_undef; }
else if (is_conflict() && at_base_level()) { LOG_H2("UNSAT"); return l_false; }
else if (is_conflict()) resolve_conflict();
else if (can_propagate()) propagate();
else if (!can_decide()) { LOG_H2("SAT"); return l_true; }
@ -141,7 +143,6 @@ namespace polysat {
void solver::del_var() {
// TODO also remove v from all learned constraints.
pvar v = m_viable.size() - 1;
m_free_vars.del_var_eh(v);
m_viable.pop_back();
m_cjust.pop_back();
m_value.pop_back();
@ -222,6 +223,8 @@ namespace polysat {
}
c->assign_eh(is_true);
add_watch(*c);
m_assign_eh_history.push_back(v);
m_trail.push_back(trail_instr_t::assign_eh_i);
c->narrow(*this);
}
@ -263,6 +266,7 @@ namespace polysat {
}
void solver::pop_levels(unsigned num_levels) {
LOG("Pop " << num_levels << " levels; current level is " << m_level);
while (num_levels > 0) {
switch (m_trail.back()) {
case trail_instr_t::qhead_i: {
@ -297,6 +301,14 @@ namespace polysat {
m_cjust_trail.pop_back();
break;
}
case trail_instr_t::assign_eh_i: {
auto bvar = m_assign_eh_history.back();
constraint* c = get_bv2c(bvar);
erase_watch(*c);
c->unassign_eh();
m_assign_eh_history.pop_back();
break;
}
default:
UNREACHABLE();
}
@ -375,7 +387,6 @@ namespace polysat {
++m_stats.m_num_decisions;
else
++m_stats.m_num_propagations;
TRACE("polysat", tout << "v" << v << " := " << val << " " << j << "\n";);
LOG("pvar " << v << " := " << val << " by " << j);
SASSERT(is_viable(v, val));
m_value[v] = val;
@ -385,15 +396,15 @@ namespace polysat {
}
void solver::set_conflict(constraint& c) {
LOG("conflict: " << c);
SASSERT(m_conflict.empty());
TRACE("polysat", tout << "conflict " << c << "\n";);
m_conflict.push_back(&c);
}
void solver::set_conflict(pvar v) {
SASSERT(m_conflict.empty());
m_conflict.append(m_cjust[v]);
TRACE("polysat", tout << "conflict "; for (auto* c : m_conflict) tout << *c << "\n";);
LOG("conflict for pvar " << v << ": " << m_conflict);
if (m_cjust[v].empty())
m_conflict.push_back(nullptr);
}
@ -440,14 +451,27 @@ namespace polysat {
if (conflict_var != null_var) {
LOG_H2("Conflict due to empty viable set for pvar " << conflict_var);
scoped_ptr_vector<constraint> disjunctive_lemma;
if (forbidden_intervals::explain(*this, m_conflict, conflict_var, disjunctive_lemma)) {
LOG_H3("Learning disjunctive lemma"); // << disjunctive_lemma);
SASSERT(disjunctive_lemma.size() > 0);
if (disjunctive_lemma.size() == 1) {
clause new_lemma;
if (forbidden_intervals::explain(*this, m_conflict, conflict_var, new_lemma)) {
LOG_H3("Learning disjunctive lemma");
SASSERT(new_lemma.size() > 0);
if (new_lemma.size() == 1) {
lemma = new_lemma.detach()[0];
// TODO: continue normally?
} else {
// TODO: solver needs to return l_undef and allow external handling of disjunctive lemma
SASSERT(m_disjunctive_lemma.empty());
reset_marks();
for (constraint* c : new_lemma) {
m_disjunctive_lemma.push_back(c->bvar());
insert_bv2c(c->bvar(), c);
for (auto v : c->vars())
set_mark(v);
}
m_redundant_clauses.push_back(std::move(new_lemma));
backtrack(m_search.size()-1, lemma);
SASSERT(pending_disjunctive_lemma());
m_conflict.reset();
return;
}
}
}
@ -635,13 +659,15 @@ namespace polysat {
}
void solver::push() {
LOG("Push user scope");
push_level();
m_base_levels.push_back(m_level);
}
void solver::pop(unsigned num_scopes) {
unsigned base_level = m_base_levels[m_base_levels.size() - num_scopes];
pop_levels(m_level - base_level - 1);
LOG("Pop " << num_scopes << " user scopes; lowest popped level = " << base_level << "; current level = " << m_level);
pop_levels(m_level - base_level + 1);
}
bool solver::at_base_level() const {