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Try to produce an op_constraint lemma before invoking the fallback solver

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This commit is contained in:
Jakob Rath 2022-11-30 12:13:47 +01:00
parent 2bc1b3a6dd
commit b4b94c954b
3 changed files with 37 additions and 18 deletions
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35
src/math/polysat/solver.cpp
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@ -633,15 +633,32 @@ namespace polysat {
/// Verify the value we're trying to assign against the univariate solver
void solver::assign_verify(pvar v, rational val, justification j) {
SASSERT(j.is_decision() || j.is_propagation());
// First, check evaluation of the currently-univariate constraints
// TODO: we should add a better way to test constraints under assignments, without modifying the solver state.
m_value[v] = val;
m_search.push_assignment(v, val);
m_justification[v] = j;
bool is_valid = m_viable_fallback.check_constraints(v);
m_search.pop();
m_justification[v] = justification::unassigned();
if (!is_valid) {
signed_constraint c;
{
// Fake the assignment v := val so we can check the constraints using the new value.
m_value[v] = val;
m_search.push_assignment(v, val);
m_justification[v] = j;
on_scope_exit _undo([&](){
m_search.pop();
m_justification[v] = justification::unassigned();
});
// Check evaluation of the currently-univariate constraints.
c = m_viable_fallback.find_violated_constraint(v);
if (c) {
LOG("Violated constraint: " << c);
// op_constraints produce lemmas rather than forbidden intervals, so give it an opportunity to
// produce a lemma before invoking the fallback solver.
if (c->is_op()) {
c.narrow(*this, false);
if (is_conflict())
return;
}
}
}
if (c) {
LOG_H2("Chosen assignment " << assignment_pp(*this, v, val) << " is not actually viable!");
++m_stats.m_num_viable_fallback;
// Try to find a valid replacement value