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adding preferred sat, currently disabled, to wmax. Fixing issue #815

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-11-30 09:52:05 -08:00
parent 441dbbb94b
commit 024082a45f
13 changed files with 887 additions and 405 deletions
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200
src/smt/smt_consequences.cpp
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@ -56,36 +56,7 @@ namespace smt {
s.insert(lit.var());
}
else {
b_justification js = get_justification(lit.var());
switch (js.get_kind()) {
case b_justification::CLAUSE: {
clause * cls = js.get_clause();
if (!cls) break;
unsigned num_lits = cls->get_num_literals();
for (unsigned j = 0; j < num_lits; ++j) {
literal lit2 = cls->get_literal(j);
if (lit2.var() != lit.var()) {
s |= m_antecedents.find(lit2.var());
}
}
break;
}
case b_justification::BIN_CLAUSE: {
s |= m_antecedents.find(js.get_literal().var());
break;
}
case b_justification::AXIOM: {
break;
}
case b_justification::JUSTIFICATION: {
literal_vector literals;
m_conflict_resolution->justification2literals(js.get_justification(), literals);
for (unsigned j = 0; j < literals.size(); ++j) {
s |= m_antecedents.find(literals[j].var());
}
break;
}
}
justify(lit, s);
}
m_antecedents.insert(lit.var(), s);
TRACE("context", display_literal_verbose(tout, lit);
@ -122,6 +93,39 @@ namespace smt {
}
}
void context::justify(literal lit, index_set& s) {
b_justification js = get_justification(lit.var());
switch (js.get_kind()) {
case b_justification::CLAUSE: {
clause * cls = js.get_clause();
if (!cls) break;
unsigned num_lits = cls->get_num_literals();
for (unsigned j = 0; j < num_lits; ++j) {
literal lit2 = cls->get_literal(j);
if (lit2.var() != lit.var()) {
s |= m_antecedents.find(lit2.var());
}
}
break;
}
case b_justification::BIN_CLAUSE: {
s |= m_antecedents.find(js.get_literal().var());
break;
}
case b_justification::AXIOM: {
break;
}
case b_justification::JUSTIFICATION: {
literal_vector literals;
m_conflict_resolution->justification2literals(js.get_justification(), literals);
for (unsigned j = 0; j < literals.size(); ++j) {
s |= m_antecedents.find(literals[j].var());
}
break;
}
}
}
void context::extract_fixed_consequences(unsigned& start, obj_map<expr, expr*>& vars, index_set const& assumptions, expr_ref_vector& conseq) {
pop_to_search_lvl();
SASSERT(!inconsistent());
@ -369,6 +373,142 @@ namespace smt {
<< ")\n";
}
void context::extract_cores(expr_ref_vector const& asms, vector<expr_ref_vector>& cores, unsigned& min_core_size) {
index_set _asms, _nasms;
u_map<expr*> var2expr;
for (unsigned i = 0; i < asms.size(); ++i) {
literal lit = get_literal(asms[i]);
_asms.insert(lit.index());
_nasms.insert((~lit).index());
var2expr.insert(lit.var(), asms[i]);
}
m_antecedents.reset();
literal_vector const& lits = assigned_literals();
for (unsigned i = 0; i < lits.size(); ++i) {
literal lit = lits[i];
index_set s;
if (_asms.contains(lit.index())) {
s.insert(lit.var());
}
else {
justify(lit, s);
}
m_antecedents.insert(lit.var(), s);
if (_nasms.contains(lit.index())) {
expr_ref_vector core(m_manager);
index_set::iterator it = s.begin(), end = s.end();
for (; it != end; ++it) {
core.push_back(var2expr[*it]);
}
core.push_back(var2expr[lit.var()]);
cores.push_back(core);
min_core_size = std::min(min_core_size, core.size());
}
}
}
void context::preferred_sat(literal_vector& lits) {
bool retry = true;
while (retry) {
retry = false;
for (unsigned i = 0; i < lits.size(); ++i) {
literal lit = lits[i];
if (lit == null_literal || get_assignment(lit) != l_undef) {
continue;
}
push_scope();
assign(lit, b_justification::mk_axiom(), true);
while (!propagate()) {
lits[i] = null_literal;
retry = true;
if (!resolve_conflict() || inconsistent()) {
SASSERT(inconsistent());
return;
}
}
}
}
}
void context::display_partial_assignment(std::ostream& out, expr_ref_vector const& asms, unsigned min_core_size) {
unsigned num_true = 0, num_false = 0, num_undef = 0;
for (unsigned i = 0; i < asms.size(); ++i) {
literal lit = get_literal(asms[i]);
if (get_assignment(lit) == l_false) {
++num_false;
}
if (get_assignment(lit) == l_true) {
++num_true;
}
if (get_assignment(lit) == l_undef) {
++num_undef;
}
}
out << "(smt.preferred-sat true: " << num_true << " false: " << num_false << " undef: " << num_undef << " min core: " << min_core_size << ")\n";
}
lbool context::preferred_sat(expr_ref_vector const& asms, vector<expr_ref_vector>& cores) {
pop_to_base_lvl();
cores.reset();
setup_context(false);
internalize_assertions();
if (m_asserted_formulas.inconsistent() || inconsistent()) {
return l_false;
}
scoped_mk_model smk(*this);
init_search();
flet<bool> l(m_searching, true);
unsigned level = m_scope_lvl;
unsigned min_core_size = UINT_MAX;
lbool is_sat = l_true;
unsigned num_restarts = 0;
while (true) {
if (m_manager.canceled()) {
is_sat = l_undef;
break;
}
literal_vector lits;
for (unsigned i = 0; i < asms.size(); ++i) {
lits.push_back(get_literal(asms[i]));
}
preferred_sat(lits);
if (inconsistent()) {
SASSERT(m_scope_lvl == level);
is_sat = l_false;
break;
}
extract_cores(asms, cores, min_core_size);
IF_VERBOSE(1, display_partial_assignment(verbose_stream(), asms, min_core_size););
if (min_core_size <= 10) {
is_sat = l_undef;
break;
}
is_sat = bounded_search();
if (!restart(is_sat, level)) {
break;
}
++num_restarts;
if (num_restarts >= min_core_size) {
is_sat = l_undef;
while (num_restarts <= 10*min_core_size) {
is_sat = bounded_search();
if (!restart(is_sat, level)) {
break;
}
++num_restarts;
}
break;
}
}
end_search();
return check_finalize(is_sat);
}
struct neg_literal {
unsigned negate(unsigned i) {
return (~to_literal(i)).index();