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fix #5468

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This commit is contained in:
Nikolaj Bjorner 2021-08-10 10:46:47 -07:00
parent 391db898d3
commit 081cdbd762
1 changed files with 21 additions and 16 deletions
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37
src/tactic/portfolio/solver_subsumption_tactic.cpp
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@ -41,31 +41,36 @@ class solver_subsumption_tactic : public tactic {
/**
* Check subsumption (a \/ b \/ c)
* if (a \/ b) is already implied
* Use a naive algorithm (not binary disection here)
* if (a \/ b) is already implied or if b is false in F
*
* If
* F |= (a \/ b \/ c)
* Then replace (a \/ b \/ c) by true
*
* If
* F |= !b
* Then replace (a \/ b \/ c) by (a \/ c)
*
*/
bool simplify(expr_ref& f) {
expr_ref_vector fmls(m), ors(m), prefix(m);
expr_ref nf(m.mk_not(f), m);
fmls.push_back(nf);
lbool is_sat = m_solver->check_sat(fmls);
if (is_sat == l_false) {
f = m.mk_true();
return true;
}
if (!m.is_or(f))
return false;
expr_ref_vector ors(m);
ors.append(to_app(f)->get_num_args(), to_app(f)->get_args());
expr_ref_vector prefix(m);
for (unsigned i = 0; i < ors.size(); ++i) {
expr_ref_vector fmls(m);
fmls.append(prefix);
for (unsigned k = i + 1; k < ors.size(); ++k)
fmls.push_back(m.mk_not(ors.get(k)));
lbool is_sat = m_solver->check_sat(fmls);
if (is_sat == l_false)
continue;
fmls.reset();
fmls.push_back(ors.get(i));
fmls.push_back(ors.get(i));
is_sat = m_solver->check_sat(fmls);
if (is_sat == l_false)
continue;
prefix.push_back(ors.get(i));
if (is_sat != l_false)
prefix.push_back(ors.get(i));
}
if (ors.size() != prefix.size()) {
ors.reset();