mirror of
https://github.com/Z3Prover/z3
synced 2025-04-08 10:25:18 +00:00
Cleanup of hypothesis_reducer
This commit is contained in:
Arie Gurfinkel
parent
2db38fedd6
commit
8d312f9d1f
|
|
@ -133,7 +133,7 @@ proof_ref theory_axiom_reducer::reduce(proof* pr) {
|
|||
SASSERT(m.get_fact(res) == m.get_fact(p));
|
||||
}
|
||||
else {
|
||||
// proof is dirty, if a subproof of one of its premises
|
||||
// proof is dirty, if a sub-proof of one of its premises
|
||||
// has been transformed
|
||||
bool dirty = false;
|
||||
|
||||
|
|
@ -173,85 +173,67 @@ proof_ref theory_axiom_reducer::reduce(proof* pr) {
|
|||
return proof_ref(res, m);
|
||||
}
|
||||
|
||||
void hypothesis_reducer::reset()
|
||||
{
|
||||
void hypothesis_reducer::reset() {
|
||||
m_cache.reset();
|
||||
m_units.reset();
|
||||
m_active_hyps.reset();
|
||||
m_parent_hyps.reset();
|
||||
for (auto t : m_pinned_active_hyps) dealloc(t);
|
||||
m_pinned_active_hyps.reset();
|
||||
for (auto t : m_pinned_parent_hyps) dealloc(t);
|
||||
m_pinned_parent_hyps.reset();
|
||||
m_pinned.reset();
|
||||
}
|
||||
|
||||
void hypothesis_reducer::compute_hypsets(proof* pr)
|
||||
{
|
||||
void hypothesis_reducer::compute_hypsets(proof *pr) {
|
||||
ptr_vector<proof> todo;
|
||||
todo.push_back(pr);
|
||||
|
||||
while (!todo.empty())
|
||||
{
|
||||
while (!todo.empty()) {
|
||||
proof* p = todo.back();
|
||||
|
||||
if (m_active_hyps.contains(p))
|
||||
{
|
||||
if (m_active_hyps.contains(p)) {
|
||||
SASSERT(m_parent_hyps.contains(p));
|
||||
todo.pop_back();
|
||||
continue;
|
||||
}
|
||||
// if we haven't already visited the current unit
|
||||
else
|
||||
{
|
||||
bool existsUnvisitedParent = false;
|
||||
|
||||
// add unprocessed premises to stack for DFS. If there is at least one unprocessed premise, don't compute the result
|
||||
// for p now, but wait until those unprocessed premises are processed.
|
||||
for (unsigned i = 0; i < m.get_num_parents(p); ++i) {
|
||||
SASSERT(m.is_proof(p->get_arg(i)));
|
||||
proof* premise = to_app(p->get_arg(i));
|
||||
bool dirty = false;
|
||||
for (unsigned i = 0, sz = m.get_num_parents(p); i < sz; ++i) {
|
||||
SASSERT(m.is_proof(p->get_arg(i)));
|
||||
proof *parent = to_app(p->get_arg(i));
|
||||
|
||||
// if we haven't visited the premise yet
|
||||
if (!m_active_hyps.contains(premise))
|
||||
{
|
||||
SASSERT(!m_parent_hyps.contains(premise));
|
||||
// add it to the stack
|
||||
todo.push_back(premise);
|
||||
existsUnvisitedParent = true;
|
||||
}
|
||||
if (!m_active_hyps.contains(parent)) {
|
||||
SASSERT(!m_parent_hyps.contains(parent));
|
||||
todo.push_back(parent);
|
||||
dirty = true;
|
||||
}
|
||||
}
|
||||
if (dirty) continue;
|
||||
|
||||
// if we already visited all premises, we can visit p too
|
||||
if (!existsUnvisitedParent)
|
||||
{
|
||||
todo.pop_back();
|
||||
todo.pop_back();
|
||||
|
||||
// create active_hyps-set and parent_hyps-set for step p
|
||||
proof_set* active_hyps = alloc(proof_set);
|
||||
m_pinned_active_hyps.insert(active_hyps);
|
||||
m_active_hyps.insert(p, active_hyps);
|
||||
// create active_hyps-set and parent_hyps-set for step p
|
||||
proof_set* active_hyps = alloc(proof_set);
|
||||
m_pinned_active_hyps.insert(active_hyps);
|
||||
m_active_hyps.insert(p, active_hyps);
|
||||
|
||||
expr_set* parent_hyps = alloc(expr_set);
|
||||
m_pinned_parent_hyps.insert(parent_hyps);
|
||||
m_parent_hyps.insert(p, parent_hyps);
|
||||
expr_set* parent_hyps = alloc(expr_set);
|
||||
m_pinned_parent_hyps.insert(parent_hyps);
|
||||
m_parent_hyps.insert(p, parent_hyps);
|
||||
|
||||
// fill both sets
|
||||
if (m.is_hypothesis(p))
|
||||
{
|
||||
active_hyps->insert(p);
|
||||
parent_hyps->insert(m.get_fact(p));
|
||||
}
|
||||
else
|
||||
{
|
||||
for (unsigned i = 0, sz = m.get_num_parents(p); i < sz; ++i)
|
||||
{
|
||||
proof* pp = m.get_parent(p, i);
|
||||
set_union(*parent_hyps, *m_parent_hyps.find(pp));
|
||||
// fill both sets
|
||||
if (m.is_hypothesis(p)) {
|
||||
active_hyps->insert(p);
|
||||
parent_hyps->insert(m.get_fact(p));
|
||||
}
|
||||
else {
|
||||
for (unsigned i = 0, sz = m.get_num_parents(p); i < sz; ++i) {
|
||||
proof* parent = m.get_parent(p, i);
|
||||
set_union(*parent_hyps, *m_parent_hyps.find(parent));
|
||||
|
||||
if (!m.is_lemma(p)) // lemmas clear all hypotheses
|
||||
{
|
||||
set_union(*active_hyps, *m_active_hyps.find(pp));
|
||||
}
|
||||
}
|
||||
}
|
||||
if (!m.is_lemma(p))
|
||||
// lemmas clear all hypotheses
|
||||
set_union(*active_hyps, *m_active_hyps.find(parent));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
@ -259,48 +241,41 @@ void hypothesis_reducer::compute_hypsets(proof* pr)
|
|||
|
||||
// collect all units that are hyp-free and are used as hypotheses somewhere
|
||||
// requires that m_active_hyps and m_parent_hyps have been computed
|
||||
void hypothesis_reducer::collect_units(proof* pr)
|
||||
{
|
||||
void hypothesis_reducer::collect_units(proof* pr) {
|
||||
expr_set* all_hyps = m_parent_hyps.find(pr);
|
||||
SASSERT(all_hyps != nullptr);
|
||||
SASSERT(all_hyps);
|
||||
|
||||
proof_post_order pit(pr, m);
|
||||
while (pit.hasNext()) {
|
||||
proof* p = pit.next();
|
||||
if (!m.is_hypothesis(p))
|
||||
{
|
||||
if (!m.is_hypothesis(p)) {
|
||||
proof_set* active_hyps = m_active_hyps.find(p);
|
||||
SASSERT(active_hyps != nullptr);
|
||||
SASSERT(active_hyps);
|
||||
|
||||
// collect units that are hyp-free and are used as hypotheses in the proof pr
|
||||
if (active_hyps->empty() && m.has_fact(p) && all_hyps->contains(m.get_fact(p)))
|
||||
{
|
||||
// collect units that are hyp-free and are used as
|
||||
// hypotheses in the proof pr
|
||||
if (active_hyps->empty() && m.has_fact(p) &&
|
||||
all_hyps->contains(m.get_fact(p)))
|
||||
m_units.insert(m.get_fact(p), p);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
proof_ref hypothesis_reducer::reduce(proof* pr)
|
||||
{
|
||||
proof_ref hypothesis_reducer::reduce(proof* pr) {
|
||||
compute_hypsets(pr);
|
||||
collect_units(pr);
|
||||
|
||||
proof* res = compute_transformed_proof(pr);
|
||||
SASSERT(res != nullptr);
|
||||
|
||||
proof_ref res_ref(res,m);
|
||||
|
||||
proof_ref res(compute_transformed_proof(pr), m);
|
||||
SASSERT(res);
|
||||
reset();
|
||||
|
||||
DEBUG_CODE(proof_checker pc(m);
|
||||
expr_ref_vector side(m);
|
||||
SASSERT(pc.check(res, side));
|
||||
);
|
||||
return res_ref;
|
||||
SASSERT(pc.check(res, side)););
|
||||
return res;
|
||||
}
|
||||
|
||||
proof* hypothesis_reducer::compute_transformed_proof(proof* pf)
|
||||
{
|
||||
proof* hypothesis_reducer::compute_transformed_proof(proof* pf) {
|
||||
proof *res = NULL;
|
||||
|
||||
ptr_vector<proof> todo;
|
||||
|
|
@ -325,204 +300,198 @@ proof* hypothesis_reducer::compute_transformed_proof(proof* pf)
|
|||
pp = m.get_parent(p, i);
|
||||
if (m_cache.find(pp, tmp)) {
|
||||
args.push_back(tmp);
|
||||
dirty = dirty || pp != tmp;
|
||||
dirty |= pp != tmp;
|
||||
} else {
|
||||
todo.push_back(pp);
|
||||
}
|
||||
}
|
||||
|
||||
if (todo_sz < todo.size()) { continue; }
|
||||
else { todo.pop_back(); }
|
||||
if (todo_sz < todo.size()) continue;
|
||||
|
||||
todo.pop_back();
|
||||
|
||||
// here the proof transformation begins
|
||||
// INV: whenever we visit p, active_hyps and parent_hyps have been computed for the args.
|
||||
if (m.is_hypothesis(p))
|
||||
{
|
||||
// transform the proof
|
||||
|
||||
// INV: whenever p is visited, active_hyps and parent_hyps
|
||||
// have already been computed for everything in args.
|
||||
if (m.is_hypothesis(p)) {
|
||||
// hyp: replace by a corresponding unit
|
||||
if (m_units.find(m.get_fact(p), tmp))
|
||||
{
|
||||
if (m_units.find(m.get_fact(p), tmp)) {
|
||||
// look up the proof of the unit:
|
||||
// if there is a transformed proof use that one
|
||||
// otherwise use the original proof
|
||||
proof* proof_of_unit;
|
||||
if (!m_cache.find(tmp,proof_of_unit))
|
||||
{
|
||||
if (!m_cache.find(tmp, proof_of_unit)) {
|
||||
proof_of_unit = tmp;
|
||||
}
|
||||
|
||||
// compute hypsets (have not been computed in general, since the unit can be anywhere in the proof)
|
||||
// compute hypsets (have not been computed in general,
|
||||
// since the unit can be anywhere in the proof)
|
||||
compute_hypsets(proof_of_unit);
|
||||
|
||||
// if the transformation doesn't create a cycle, perform it
|
||||
SASSERT(m_parent_hyps.contains(proof_of_unit));
|
||||
expr_set* parent_hyps = m_parent_hyps.find(proof_of_unit);
|
||||
if (!parent_hyps->contains(p))
|
||||
{
|
||||
res = proof_of_unit;
|
||||
// hypsets have already been computed for proof_of_unit
|
||||
}
|
||||
// otherwise don't transform the proof and just use the hypothesis
|
||||
res = proof_of_unit;
|
||||
// otherwise don't transform the proof and just use
|
||||
// the hypothesis
|
||||
else
|
||||
{
|
||||
res = p;
|
||||
// hypsets have already been computed for p
|
||||
}
|
||||
res = p;
|
||||
}
|
||||
else
|
||||
{
|
||||
res = p;
|
||||
// hypsets have already been computed for p
|
||||
}
|
||||
res = p;
|
||||
}
|
||||
else if (!dirty) { res = p; }
|
||||
|
||||
else if (m.is_lemma(p))
|
||||
{
|
||||
//lemma: reduce the premise; remove reduced consequences from conclusion
|
||||
else if (!dirty)
|
||||
res = p;
|
||||
else if (m.is_lemma(p)) {
|
||||
//lemma: reduce the premise; remove reduced consequences
|
||||
//from conclusion
|
||||
SASSERT(args.size() == 1);
|
||||
res = mk_lemma_core(args[0], m.get_fact(p));
|
||||
compute_hypsets(res);
|
||||
}
|
||||
else if (m.is_unit_resolution(p))
|
||||
{
|
||||
// unit: reduce untis; reduce the first premise; rebuild unit resolution
|
||||
else if (m.is_unit_resolution(p)) {
|
||||
// unit: reduce untis; reduce the first premise; rebuild
|
||||
// unit resolution
|
||||
res = mk_unit_resolution_core(args);
|
||||
compute_hypsets(res);
|
||||
}
|
||||
else
|
||||
{
|
||||
res = mk_step_core(p, args);
|
||||
else {
|
||||
res = mk_proof_core(p, args);
|
||||
compute_hypsets(res);
|
||||
}
|
||||
|
||||
SASSERT(res);
|
||||
m_cache.insert(p, res);
|
||||
|
||||
// bail out as soon as found a sub-proof of false
|
||||
SASSERT(m_active_hyps.contains(res));
|
||||
proof_set* active_hyps = m_active_hyps.find(res);
|
||||
if (active_hyps->empty() && m.has_fact(res) && m.is_false(m.get_fact(res)))
|
||||
{
|
||||
return res;
|
||||
}
|
||||
}
|
||||
UNREACHABLE();
|
||||
return nullptr;
|
||||
}
|
||||
|
||||
proof* hypothesis_reducer::mk_lemma_core(proof* premise, expr *fact)
|
||||
{
|
||||
proof* hypothesis_reducer::mk_lemma_core(proof* premise, expr *fact) {
|
||||
SASSERT(m.is_false(m.get_fact(premise)));
|
||||
|
||||
SASSERT(m_active_hyps.contains(premise));
|
||||
|
||||
proof_set* active_hyps = m_active_hyps.find(premise);
|
||||
|
||||
// if there is no active hypothesis return the premise
|
||||
if (active_hyps->empty())
|
||||
{
|
||||
if (active_hyps->empty()) {
|
||||
// XXX just in case premise might go away
|
||||
m_pinned.push_back(premise);
|
||||
return premise;
|
||||
}
|
||||
// otherwise build disjunction of the negated active hypothesis' and add lemma step.
|
||||
else
|
||||
{
|
||||
expr_ref_buffer args(m);
|
||||
for (auto hyp : *active_hyps)
|
||||
{
|
||||
expr* hyp_fact = m.get_fact(hyp);
|
||||
expr_ref negated_hyp_fact(m);
|
||||
negated_hyp_fact = m.is_not(hyp_fact) ? to_app(hyp_fact)->get_arg(0) : m.mk_not(hyp_fact);
|
||||
args.push_back(negated_hyp_fact);
|
||||
}
|
||||
|
||||
expr_ref lemma(m);
|
||||
if (args.size() == 1)
|
||||
{
|
||||
lemma = args[0];
|
||||
}
|
||||
// otherwise, build a disjunction of the negated active hypotheses
|
||||
// and add a lemma proof step
|
||||
expr_ref_buffer args(m);
|
||||
for (auto hyp : *active_hyps) {
|
||||
expr *hyp_fact, *t;
|
||||
hyp_fact = m.get_fact(hyp);
|
||||
if (m.is_not(hyp_fact, t))
|
||||
args.push_back(t);
|
||||
else
|
||||
{
|
||||
lemma = m.mk_or(args.size(), args.c_ptr());
|
||||
}
|
||||
proof_ref res(m);
|
||||
res = m.mk_lemma(premise, lemma);
|
||||
m_pinned.push_back(res);
|
||||
return res;
|
||||
args.push_back(m.mk_not(hyp_fact));
|
||||
}
|
||||
|
||||
expr_ref lemma(m);
|
||||
lemma = mk_or(m, args.size(), args.c_ptr());
|
||||
|
||||
proof* res;
|
||||
res = m.mk_lemma(premise, lemma);
|
||||
m_pinned.push_back(res);
|
||||
return res;
|
||||
}
|
||||
|
||||
proof* hypothesis_reducer::mk_unit_resolution_core(ptr_buffer<proof>& args)
|
||||
{
|
||||
ptr_buffer<proof> pf_args; // the arguments of the transformed unit resolution step
|
||||
pf_args.push_back(args [0]); // the first element of args is the clause to resolve with
|
||||
|
||||
proof* hypothesis_reducer::mk_unit_resolution_core(ptr_buffer<proof>& args) {
|
||||
// if any literal is false, we don't need a unit resolution step
|
||||
// could be the case due to transformations which already have been done
|
||||
for (unsigned i = 1; i < args.size(); ++i)
|
||||
{
|
||||
if (m.is_false(m.get_fact(args[i])))
|
||||
{
|
||||
// This can be the case due to some previous transformations
|
||||
for (unsigned i = 1, sz = args.size(); i < sz; ++i) {
|
||||
if (m.is_false(m.get_fact(args[i]))) {
|
||||
// XXX just in case
|
||||
m_pinned.push_back(args[i]);
|
||||
return args[i];
|
||||
}
|
||||
}
|
||||
|
||||
app *cls_fact = to_app(m.get_fact(args[0])); // BUG: I guess this shouldn't work with quantifiers (since they are no apps)
|
||||
ptr_buffer<expr> cls;
|
||||
if (m.is_or(cls_fact)) {
|
||||
for (unsigned i = 0, sz = cls_fact->get_num_args(); i < sz; ++i)
|
||||
{ cls.push_back(cls_fact->get_arg(i)); }
|
||||
} else { cls.push_back(cls_fact); }
|
||||
proof* arg0 = args[0];
|
||||
ptr_buffer<proof> pf_args;
|
||||
pf_args.push_back(arg0);
|
||||
|
||||
// construct new resolvent
|
||||
ptr_buffer<expr> new_fact_cls;
|
||||
// BUG: I guess this shouldn't work with quantifiers (since they
|
||||
// are not apps)
|
||||
// AG: who is "I"? What is the bug?
|
||||
app *fact = to_app(m.get_fact(arg0));
|
||||
ptr_buffer<expr> cls;
|
||||
if (m.is_or(fact)) {
|
||||
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;
|
||||
bool found;
|
||||
// XXX quadratic
|
||||
|
||||
// -- find all literals that are resolved on
|
||||
// XXX quadratic implementation
|
||||
for (unsigned i = 0, sz = cls.size(); i < sz; ++i) {
|
||||
found = false;
|
||||
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;
|
||||
pf_args.push_back(args [j]);
|
||||
pf_args.push_back(args[j]);
|
||||
break;
|
||||
}
|
||||
}
|
||||
if (!found) {
|
||||
new_fact_cls.push_back(cls.get(i));
|
||||
}
|
||||
if (!found) new_fact.push_back(cls.get(i));
|
||||
}
|
||||
|
||||
SASSERT(new_fact_cls.size() + pf_args.size() - 1 == cls.size());
|
||||
expr_ref new_fact(m);
|
||||
new_fact = mk_or(m, new_fact_cls.size(), new_fact_cls.c_ptr());
|
||||
SASSERT(new_fact.size() + pf_args.size() - 1 == cls.size());
|
||||
|
||||
// create new proof step
|
||||
if (pf_args.size() == 1) // the only premise is the clause itself
|
||||
{
|
||||
return args[0];
|
||||
}
|
||||
else
|
||||
{
|
||||
proof* res = m.mk_unit_resolution(pf_args.size(), pf_args.c_ptr(), new_fact);
|
||||
m_pinned.push_back(res);
|
||||
return res;
|
||||
// unit resolution got reduced to noop
|
||||
if (pf_args.size() == 1) {
|
||||
// XXX just in case
|
||||
m_pinned.push_back(arg0);
|
||||
return arg0;
|
||||
}
|
||||
|
||||
// make unit resolution proof step
|
||||
expr_ref tmp(m);
|
||||
tmp = mk_or(m, new_fact.size(), new_fact.c_ptr());
|
||||
proof* res = m.mk_unit_resolution(pf_args.size(), pf_args.c_ptr(), tmp);
|
||||
m_pinned.push_back(res);
|
||||
return res;
|
||||
}
|
||||
|
||||
proof* hypothesis_reducer::mk_step_core(proof* old_step, ptr_buffer<proof>& args)
|
||||
{
|
||||
// if any of the literals is false, we don't need a step
|
||||
for (unsigned i = 0; i < args.size(); ++i)
|
||||
{
|
||||
if (m.is_false(m.get_fact(args[i])))
|
||||
{
|
||||
proof* hypothesis_reducer::mk_proof_core(proof* old, ptr_buffer<proof>& args) {
|
||||
// if any of the literals are false, we don't need a step
|
||||
for (unsigned i = 0; i < args.size(); ++i) {
|
||||
if (m.is_false(m.get_fact(args[i]))) {
|
||||
// XXX just in case
|
||||
m_pinned.push_back(args[i]);
|
||||
return args[i];
|
||||
}
|
||||
}
|
||||
|
||||
// otherwise build step
|
||||
args.push_back(to_app(m.get_fact(old_step))); // BUG: I guess this doesn't work with quantifiers (since they are no apps)
|
||||
// BUG: I guess this doesn't work with quantifiers (since they are no apps)
|
||||
args.push_back(to_app(m.get_fact(old)));
|
||||
|
||||
SASSERT(old_step->get_decl()->get_arity() == args.size());
|
||||
proof* res = m.mk_app(old_step->get_decl(), args.size(), (expr * const*)args.c_ptr());
|
||||
SASSERT(old->get_decl()->get_arity() == args.size());
|
||||
|
||||
proof* res = m.mk_app(old->get_decl(), args.size(),
|
||||
(expr * const*)args.c_ptr());
|
||||
m_pinned.push_back(res);
|
||||
return res;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -46,10 +46,12 @@ private:
|
|||
void reset();
|
||||
};
|
||||
|
||||
/// reduces the number of hypotheses in a proof
|
||||
class hypothesis_reducer
|
||||
{
|
||||
public:
|
||||
hypothesis_reducer(ast_manager &m) : m(m), m_pinned(m) {}
|
||||
~hypothesis_reducer() {reset();}
|
||||
|
||||
// reduce hypothesis and return transformed proof
|
||||
proof_ref reduce(proof* pf);
|
||||
|
|
@ -90,7 +92,7 @@ private:
|
|||
|
||||
proof* mk_lemma_core(proof *pf, expr *fact);
|
||||
proof* mk_unit_resolution_core(ptr_buffer<proof>& args);
|
||||
proof* mk_step_core(proof* old_step, ptr_buffer<proof>& args);
|
||||
proof* mk_proof_core(proof* old, ptr_buffer<proof>& args);
|
||||
};
|
||||
}
|
||||
#endif
|
||||
|
|
|
|||
Loading…
Reference in a new issue