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Fix handling of complex literals in hypothesis_reducer

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In Z3, an arbitrary, even propositional, formula can be a literal.

This requires careful handling of restructuring of unit resolution.
This commit is contained in:
Arie Gurfinkel 2018-05-17 17:01:02 -07:00
parent d1a7c0ceb0
commit 0fe5e6c2a6
1 changed files with 35 additions and 30 deletions
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43
src/muz/spacer/spacer_proof_utils.cpp
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@ -432,29 +432,34 @@ proof* hypothesis_reducer::mk_unit_resolution_core(ptr_buffer<proof>& args) {
} }
proof* arg0 = args[0]; proof* arg0 = args[0];
app *fact0 = to_app(m.get_fact(arg0));
ptr_buffer<proof> pf_args; ptr_buffer<proof> pf_args;
ptr_buffer<expr> pf_fact;
pf_args.push_back(arg0); pf_args.push_back(arg0);
// BUG: I guess this shouldn't work with quantifiers (since they // check if fact0 can be resolved as a unit
// are not apps) // this is required for handling literals with OR
// AG: who is "I"? What is the bug? for (unsigned j = 1; j < args.size(); ++j) {
app *fact = to_app(m.get_fact(arg0)); if (m.is_complement(fact0, m.get_fact(args[j]))) {
ptr_buffer<expr> cls; pf_args.push_back(args[j]);
if (m.is_or(fact)) { break;
for (unsigned i = 0, sz = fact->get_num_args(); i < sz; ++i) }
cls.push_back(fact->get_arg(i));
} }
else
cls.push_back(fact);
// construct the new resolvent
ptr_buffer<expr> new_fact; // if failed to find a resolvent, and the fact is a disjunction,
bool found; // attempt to resolve each disjunct
if (pf_args.size() == 1 && m.is_or(fact0)) {
ptr_buffer<expr> cls;
for (unsigned i = 0, sz = fact0->get_num_args(); i < sz; ++i)
cls.push_back(fact0->get_arg(i));
// -- find all literals that are resolved on // -- find all literals that are resolved on
// XXX quadratic implementation // XXX quadratic implementation
for (unsigned i = 0, sz = cls.size(); i < sz; ++i) { for (unsigned i = 0, sz = cls.size(); i < sz; ++i) {
found = false; bool found = false;
for (unsigned j = 1; j < args.size(); ++j) { for (unsigned j = 1; j < args.size(); ++j) {
if (m.is_complement(cls.get(i), m.get_fact(args[j]))) { if (m.is_complement(cls.get(i), m.get_fact(args[j]))) {
found = true; found = true;
@ -462,21 +467,21 @@ proof* hypothesis_reducer::mk_unit_resolution_core(ptr_buffer<proof>& args) {
break; break;
} }
} }
if (!found) new_fact.push_back(cls.get(i)); if (!found) pf_fact.push_back(cls.get(i));
}
SASSERT(pf_fact.size() + pf_args.size() - 1 == cls.size());
} }
SASSERT(new_fact.size() + pf_args.size() - 1 == cls.size());
// unit resolution got reduced to noop // unit resolution got reduced to noop
if (pf_args.size() == 1) { if (pf_args.size() == 1) {
// XXX just in case // XXX pin just in case
m_pinned.push_back(arg0); m_pinned.push_back(arg0);
return arg0; return arg0;
} }
// make unit resolution proof step // make unit resolution proof step
expr_ref tmp(m); expr_ref tmp(m);
tmp = mk_or(m, new_fact.size(), new_fact.c_ptr()); tmp = mk_or(m, pf_fact.size(), pf_fact.c_ptr());
proof* res = m.mk_unit_resolution(pf_args.size(), pf_args.c_ptr(), tmp); proof* res = m.mk_unit_resolution(pf_args.size(), pf_args.c_ptr(), tmp);
m_pinned.push_back(res); m_pinned.push_back(res);
return res; return res;