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fix solver-subsumption again, #5468 (negation was swapped in original wrong subsumption check, then soundness fix removed core subsumption functionality)

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-08-11 04:36:48 -07:00
parent 7ab7b8646b
commit 4f2211baab
1 changed files with 16 additions and 11 deletions
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27
src/tactic/portfolio/solver_subsumption_tactic.cpp
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@ -41,20 +41,19 @@ class solver_subsumption_tactic : public tactic {
/**
* Check subsumption (a \/ b \/ c)
* if (a \/ b) is already implied or if b is false in F
*
* If
* F |= (a \/ ~b \/ c)
* Then replace (a \/ b \/ c) by (a \/ c)
*
* 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_vector fmls(m), ors(m), nprefix(m), prefix(m);
expr_ref nf(m.mk_not(f), m);
fmls.push_back(nf);
lbool is_sat = m_solver->check_sat(fmls);
@ -65,12 +64,18 @@ class solver_subsumption_tactic : public tactic {
if (!m.is_or(f))
return false;
ors.append(to_app(f)->get_num_args(), to_app(f)->get_args());
for (expr* arg : ors)
nprefix.push_back(mk_not(m, arg));
for (unsigned i = 0; i < ors.size(); ++i) {
fmls.reset();
fmls.push_back(ors.get(i));
is_sat = m_solver->check_sat(fmls);
if (is_sat != l_false)
prefix.push_back(ors.get(i));
expr* arg = ors.get(i);
expr_ref save(nprefix.get(i), m);
nprefix[i] = arg;
is_sat = m_solver->check_sat(nprefix);
nprefix[i] = save;
if (is_sat == l_false)
nprefix[i] = m.mk_true();
else
prefix.push_back(arg);
}
if (ors.size() != prefix.size()) {
ors.reset();