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spacer_context: skolemize quant vars before renaming

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Skolemization has to be done before renaming, otherwise,
can't guarantee that variable names do not clash
This commit is contained in:
Arie Gurfinkel 2018-05-21 14:18:11 -07:00
parent 38a45f5482
commit 8be03f7c1f
2 changed files with 46 additions and 31 deletions
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73
src/muz/spacer/spacer_context.cpp
View file

@ -72,34 +72,17 @@ pob::pob (pob* parent, pred_transformer& pt,
void pob::set_post(expr* post) {
app_ref_vector b(get_ast_manager());
set_post(post, b);
app_ref_vector empty_binding(get_ast_manager());
set_post(post, empty_binding);
}
void pob::set_post(expr* post, app_ref_vector const &b) {
void pob::set_post(expr* post, app_ref_vector const &binding) {
normalize(post, m_post,
m_pt.get_context().get_params().spacer_simplify_pob(),
m_pt.get_context().get_params().spacer_use_eqclass());
m_binding.reset();
if (b.empty()) return;
m_binding.append(b);
std::sort (m_binding.c_ptr(), m_binding.c_ptr() + m_binding.size(), sk_lt_proc());
// skolemize implicit existential quantifier
ast_manager &m = get_ast_manager();
app_ref_vector pinned(m);
expr_safe_replace sub(m);
for (unsigned i = 0, sz = m_binding.size(); i < sz; ++i) {
expr* e;
e = m_binding.get(i);
pinned.push_back (mk_zk_const (m, i, get_sort(e)));
sub.insert (e, pinned.back());
}
sub(m_post);
if (!binding.empty()) {m_binding.append(binding);}
}
void pob::inherit(pob const &p) {
@ -216,6 +199,25 @@ pob *derivation::create_first_child (model_evaluator_util &mev)
return create_next_child(mev);
}
void derivation::exist_skolemize(expr* fml, app_ref_vector &vars, expr_ref &res) {
ast_manager &m = get_ast_manager();
if (vars.empty()) {res = fml; return;}
if (m.is_true(fml) || m.is_false(fml)) {res = fml; return;}
std::sort (vars.c_ptr(), vars.c_ptr() + vars.size(), sk_lt_proc());
app_ref_vector pinned(m);
expr_safe_replace sub(m);
for (unsigned i = 0, sz = vars.size(); i < sz; ++i) {
expr* e;
e = vars.get(i);
pinned.push_back (mk_zk_const (m, i, get_sort(e)));
sub.insert (e, pinned.back());
}
sub(fml, res);
}
pob *derivation::create_next_child (model_evaluator_util &mev)
{
timeit _timer (is_trace_enabled("spacer_timeit"),
@ -280,6 +282,11 @@ pob *derivation::create_next_child (model_evaluator_util &mev)
m_evars.append (vars);
}
if (!m_evars.empty()) {
// existentially quantify out m_evars from post and skolemize the result
exist_skolemize(post.get(), m_evars, post);
}
get_manager ().formula_o2n (post.get (), post,
m_premises [m_active].get_oidx (), m_evars.empty());
@ -290,7 +297,6 @@ pob *derivation::create_next_child (model_evaluator_util &mev)
pob *n = m_premises[m_active].pt().mk_pob(&m_parent,
prev_level (m_parent.level ()),
m_parent.depth (), post, m_evars);
IF_VERBOSE (1, verbose_stream ()
<< "\n\tcreate_child: " << n->pt ().head ()->get_name ()
<< " (" << n->level () << ", " << n->depth () << ") "
@ -895,9 +901,8 @@ bool pred_transformer::propagate_to_next_level (unsigned src_level)
{return m_frames.propagate_to_next_level (src_level);}
/// \brief adds a lema to the solver and to child solvers
void pred_transformer::add_lemma_core(lemma* lemma,
bool ground_only)
/// \brief adds a lemma to the solver and to child solvers
void pred_transformer::add_lemma_core(lemma* lemma, bool ground_only)
{
unsigned lvl = lemma->level();
expr* l = lemma->get_expr();
@ -1859,13 +1864,13 @@ void pred_transformer::frames::simplify_formulas ()
// ensure that the lemmas are sorted
sort();
ast_manager &m = m_pt.get_ast_manager ();
ast_manager &m = m_pt.get_ast_manager();
tactic_ref simplifier = mk_unit_subsumption_tactic (m);
tactic_ref simplifier = mk_unit_subsumption_tactic(m);
lemma_ref_vector new_lemmas;
unsigned lemmas_size = m_lemmas.size ();
goal_ref g (alloc (goal, m, false, false, false));
unsigned lemmas_size = m_lemmas.size();
goal_ref g(alloc (goal, m, false, false, false));
unsigned j = 0;
// for every frame + infinity frame
@ -1933,6 +1938,11 @@ void pred_transformer::frames::simplify_formulas ()
<< mk_pp(m_lemmas[n]->get_expr(), m)
<< "\n";
}
verbose_stream() << "Simplified goal is:\n";
for (unsigned k = 0; k < r->size(); ++k)
verbose_stream() << k << ": "
<< mk_pp(r->form(k), m) << "\n";
}
ENSURE(found);
SASSERT(found);
@ -3013,7 +3023,8 @@ lbool context::expand_pob(pob& n, pob_ref_buffer &out)
TRACE ("spacer",
tout << "expand-pob: " << n.pt().head()->get_name()
<< " level: " << n.level()
<< " depth: " << (n.depth () - m_pob_queue.min_depth ()) << "\n"
<< " depth: " << (n.depth () - m_pob_queue.min_depth ())
<< " fvsz: " << n.get_free_vars_size() << "\n"
<< mk_pp(n.post(), m) << "\n";);
STRACE ("spacer.expand-add",
@ -3450,6 +3461,8 @@ bool context::create_children(pob& n, datalog::rule const& r,
tout << "Implicant\n";
tout << mk_and (Phi) << "\n";
tout << "Projected Implicant\n" << mk_pp (phi1, m) << "\n";
if (!vars.empty())
tout << "could not eliminate: " << vars << "\n";
);
// expand literals. Ideally, we do not want to split aliasing

4
src/muz/spacer/spacer_context.h
View file

@ -517,7 +517,7 @@ public:
expr* post() const { return m_post.get (); }
void set_post(expr *post);
void set_post(expr *post, app_ref_vector const &b);
void set_post(expr *post, app_ref_vector const &binding);
/// indicate that a new post should be set for the node
void new_post(expr *post) {if(post != m_post) {m_new_post = post;}}
@ -648,6 +648,8 @@ public:
/// premise must be consistent with the transition relation
pob *create_next_child ();
/// existentially quantify vars and skolemize the result
void exist_skolemize(expr *fml, app_ref_vector &vars, expr_ref &res);
datalog::rule const& get_rule () const { return m_rule; }
pob& get_parent () const { return m_parent; }
ast_manager &get_ast_manager () const {return m_parent.get_ast_manager ();}