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fix to proof hypothesis removal facility reported by Arie Gurfinkel

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2012-12-28 16:40:29 -08:00
parent 1dfea1324e
commit 9f2743309f
4 changed files with 65 additions and 311 deletions
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41
src/muz_qe/proof_utils.cpp
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@ -223,7 +223,7 @@ public:
found_false = true;
break;
}
// SASSERT(m.get_fact(tmp) == m.get_fact(m.get_parent(p, i)));
SASSERT(m.get_fact(tmp) == m.get_fact(m.get_parent(p, i)));
parents.push_back(tmp);
if (is_closed(tmp) && !m_units.contains(m.get_fact(tmp))) {
m_units.insert(m.get_fact(tmp), tmp);
@ -235,6 +235,7 @@ public:
break;
}
tmp = m.get_parent(p, 0);
expr* old_clause = m.get_fact(tmp);
elim(tmp);
parents[0] = tmp;
expr* clause = m.get_fact(tmp);
@ -244,6 +245,31 @@ public:
pop();
break;
}
//
// case where clause is a literal in the old clause.
//
if (is_literal_in_clause(clause, old_clause)) {
bool found = false;
for (unsigned i = 1; !found && i < parents.size(); ++i) {
if (m.is_complement(clause, m.get_fact(parents[i].get()))) {
parents[1] = parents[i];
parents.resize(2);
result = m.mk_unit_resolution(parents.size(), parents.c_ptr());
m_refs.push_back(result);
add_hypotheses(result);
found = true;
}
}
if (!found) {
result = parents[0].get();
}
pop();
break;
}
//
// case where new clause is a subset of old clause.
// the literals in clause should be a subset of literals in old_clause.
//
get_literals(clause);
for (unsigned i = 1; i < parents.size(); ++i) {
bool found = false;
@ -309,6 +335,19 @@ public:
m_cache.insert(p, result);
p = result;
}
bool is_literal_in_clause(expr* fml, expr* clause) {
if (!m.is_or(clause)) {
return false;
}
app* cl = to_app(clause);
for (unsigned i = 0; i < cl->get_num_args(); ++i) {
if (cl->get_argi(i) == fml) {
return true;
}
}
return false;
}
};
void proof_utils::reduce_hypotheses(proof_ref& pr) {