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fix #6748

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destructive equality resolution uses an occurs check function that is only safe for quantifier-free formulas. In the special case where a bound variable is Boolean and occurs on a side of an equality the other side cannot have a quantifier.
This commit is contained in:
Nikolaj Bjorner 2023-06-07 15:59:25 -07:00
parent 57e92b2a59
commit 06a8987314
2 changed files with 3 additions and 3 deletions
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4
src/ast/rewriter/der.cpp
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@ -176,9 +176,9 @@ void der::reduce1(quantifier * q, expr_ref & r, proof_ref & pr) {
var * v = nullptr;
expr_ref t(m);
if (is_forall(q) && is_var_diseq(e, num_decls, v, t) && !occurs(v, t))
if (is_forall(q) && is_var_diseq(e, num_decls, v, t) && !has_quantifiers(t) && !occurs(v, t))
r = m.mk_false();
else if (is_exists(q) && is_var_eq(e, num_decls, v, t) && !occurs(v, t))
else if (is_exists(q) && is_var_eq(e, num_decls, v, t) && !has_quantifiers(t) && !occurs(v, t))
r = m.mk_true();
else {
expr_ref_vector literals(m);