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Polysat disjunctive lemmas (WIP) (#5275)

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* Extend search state by boolean literals

* Only resolve against positive equality

* mk_dep_ref

* Make clause non-owning

* scoped_clause

* Use scoped_clause

* minor

* scoped_ptr move assignment

* WIP: internal handling of disjunctive constraints

* leaf_value

* disjunctive constraints continued

* Fix bool_lit

* Actually add constraints to storage

* Some fixes

* more fixes

* constraint should have a bool_lit instead of a bool_var

* propagate(bool_lit)

* updates

* interface changes

* small fixes

* Make sat::dimacs_lit's constructor explicit

(otherwise, calling operator<< with sat::literal is ambiguous)

* Use sat::literal

* Print test name at the beginning

* Convention: constraint corresponds to the positive boolean literal

* Make constraint ownership more explicit

* clause stores literals
This commit is contained in:
Jakob Rath 2021-05-21 22:50:25 +02:00 • committed by GitHub
parent 49e9782238
commit 28996429df
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24 changed files with 1196 additions and 360 deletions
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43
src/math/polysat/forbidden_intervals.cpp
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@ -62,7 +62,7 @@ namespace polysat {
return true;
}
bool forbidden_intervals::explain(solver& s, ptr_vector<constraint> const& conflict, pvar v, clause& out_lemma) {
bool forbidden_intervals::explain(solver& s, ptr_vector<constraint> const& conflict, pvar v, scoped_clause& out_lemma) {
// Extract forbidden intervals from conflicting constraints
vector<fi_record> records;
@ -99,7 +99,16 @@ namespace polysat {
// => the side conditions of that interval are enough to produce a conflict
auto& full_record = records.back();
SASSERT(full_record.interval.is_full());
out_lemma = std::move(full_record.neg_cond);
sat::literal_vector literals;
scoped_ptr_vector<constraint> new_constraints;
literals.push_back(~sat::literal(full_record.src->bvar())); // TODO: only do this if it's not a base-level constraint! (from unit clauses, e.g., external constraints)
if (full_record.neg_cond) {
literals.push_back(sat::literal(full_record.neg_cond.get()->bvar()));
new_constraints.push_back(full_record.neg_cond.detach());
}
unsigned lemma_lvl = full_record.src->level();
p_dependency_ref lemma_dep(full_record.src->dep(), s.m_dm);
out_lemma = scoped_clause(clause::from_literals(lemma_lvl, lemma_dep, literals), std::move(new_constraints));
return true;
}
@ -130,11 +139,22 @@ namespace polysat {
// Create lemma
// Idea:
// - If the side conditions hold, and
// - If the src constraints hold, and
// - if the side conditions hold, and
// - the upper bound of each interval is contained in the next interval,
// then the forbidden intervals cover the whole domain and we have a conflict.
// We learn the negation of this conjunction.
scoped_ptr_vector<constraint> literals;
sat::literal_vector literals;
scoped_ptr_vector<constraint> new_constraints;
// Add negation of src constraints as antecedents (may be resolved during backtracking)
for (unsigned const i : seq) {
// TODO: don't add base-level constraints! (from unit clauses, e.g., external constraints)
// (maybe extract that into a helper function on 'clause'... it could sort out base-level and other constraints; add the first to lemma_dep and the other to antecedents)
sat::literal src_lit{records[i].src->bvar()};
literals.push_back(~src_lit);
}
// Add side conditions and interval constraints
for (unsigned seq_i = seq.size(); seq_i-- > 0; ) {
unsigned const i = seq[seq_i];
unsigned const next_i = seq[(seq_i+1) % seq.size()];
@ -145,17 +165,20 @@ namespace polysat {
auto const& next_hi = records[next_i].interval.hi();
auto const& lhs = hi - next_lo;
auto const& rhs = next_hi - next_lo;
constraint* c = constraint::ult(lemma_lvl, s.m_next_bvar++, neg_t, lhs, rhs, lemma_dep);
scoped_ptr<constraint> c = s.m_constraints.ult(lemma_lvl, neg_t, lhs, rhs, s.mk_dep_ref(null_dependency));
LOG("constraint: " << *c);
literals.push_back(c);
literals.push_back(sat::literal(c->bvar()));
new_constraints.push_back(c.detach());
// Side conditions
// TODO: check whether the condition is subsumed by c? maybe at the end do a "lemma reduction" step, to try and reduce branching?
scoped_ptr<constraint>& neg_cond = records[i].neg_cond;
if (neg_cond)
literals.push_back(neg_cond.detach());
if (neg_cond) {
literals.push_back(sat::literal(neg_cond->bvar()));
new_constraints.push_back(neg_cond.detach());
}
}
out_lemma = std::move(literals);
scoped_ptr<clause> cl = clause::from_literals(lemma_lvl, lemma_dep, literals);
out_lemma = scoped_clause(std::move(cl), std::move(new_constraints));
return true;
}