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add detection of non-fixed variables to consequence finding

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-07-30 19:12:41 -07:00
parent 7562efbe84
commit cb2d8d2107
10 changed files with 188 additions and 25 deletions
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59
src/smt/smt_consequences.cpp
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@ -102,6 +102,47 @@ namespace smt {
}
}
void context::delete_unfixed(obj_map<expr, expr*>& var2val) {
ast_manager& m = m_manager;
ptr_vector<expr> to_delete;
obj_map<expr,expr*>::iterator it = var2val.begin(), end = var2val.end();
for (; it != end; ++it) {
expr* k = it->m_key;
expr* v = it->m_value;
if (m.is_bool(k)) {
literal lit = get_literal(k);
switch (get_assignment(lit)) {
case l_true:
if (m.is_false(v)) {
to_delete.push_back(k);
}
else {
force_phase(lit.var(), false);
}
break;
case l_false:
if (m.is_true(v)) {
to_delete.push_back(k);
}
else {
force_phase(lit.var(), true);
}
break;
default:
to_delete.push_back(k);
break;
}
}
else if (e_internalized(k) && m.are_distinct(v, get_enode(k)->get_root()->get_owner())) {
to_delete.push_back(k);
}
}
IF_VERBOSE(1, verbose_stream() << "(get-consequences deleting: " << to_delete.size() << " num-values: " << var2val.size() << ")\n";);
for (unsigned i = 0; i < to_delete.size(); ++i) {
var2val.remove(to_delete[i]);
}
}
lbool context::get_consequences(expr_ref_vector const& assumptions,
expr_ref_vector const& vars, expr_ref_vector& conseq) {
@ -135,7 +176,10 @@ namespace smt {
tout << "vars: " << vars.size() << "\n";
tout << "lits: " << num_units << "\n";);
m_case_split_queue->init_search_eh();
unsigned num_iterations = 0;
unsigned model_threshold = 2;
while (!var2val.empty()) {
++num_iterations;
obj_map<expr,expr*>::iterator it = var2val.begin();
expr* e = it->m_key;
expr* val = it->m_value;
@ -177,6 +221,17 @@ namespace smt {
else {
TRACE("context", tout << "Fixed: " << mk_pp(e, m) << "\n";);
}
TRACE("context", tout << "Unfixed variables: " << var2val.size() << "\n";);
if (model_threshold <= num_iterations) {
delete_unfixed(var2val);
// The next time we check the model is after 1.5 additional iterations.
model_threshold *= 3;
model_threshold /= 2;
}
// repeat until we either have a model with negated literal or
// the literal is implied at base.
extract_fixed_consequences(num_units, var2val, _assumptions, conseq);
num_units = assigned_literals().size();
if (var2val.contains(e)) {
@ -189,10 +244,8 @@ namespace smt {
SASSERT(get_assignment(lit) == l_false);
}
// repeat until we either have a model with negated literal or
// the literal is implied at base.
TRACE("context", tout << "Unfixed variables: " << var2val.size() << "\n";);
}
end_search();
return l_true;
}