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fix bug in blocked clause elimination: it was ignoring unit literals

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2018-03-31 13:26:20 -07:00
parent aa2721517b
commit 55eb11d91b
5 changed files with 33 additions and 37 deletions
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20
src/sat/sat_model_converter.cpp
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@ -79,21 +79,27 @@ namespace sat {
//SASSERT(!m_solver || m_solver->check_clauses(m));
while (it != begin) {
--it;
SASSERT(it->get_kind() != ELIM_VAR || m[it->var()] == l_undef);
// if it->get_kind() == BLOCK_LIT, then it might be the case that m[it->var()] != l_undef,
bool_var v0 = it->var();
SASSERT(it->get_kind() != ELIM_VAR || m[v0] == l_undef);
// if it->get_kind() == BLOCK_LIT, then it might be the case that m[v] != l_undef,
// and the following procedure flips its value.
bool sat = false;
bool var_sign = false;
unsigned index = 0;
literal_vector clause;
VERIFY(legal_to_flip(it->var()));
VERIFY(legal_to_flip(v0));
for (literal l : it->m_clauses) {
if (l == null_literal) {
// end of clause
if (v0 == 36858)
IF_VERBOSE(0, verbose_stream() << "clause: " << clause << "\n";
for (literal lit : clause) verbose_stream() << m[lit.var()] << " ";
verbose_stream() << "\n";);
elim_stack* st = it->m_elim_stack[index];
if (!sat) {
VERIFY(legal_to_flip(it->var()));
m[it->var()] = var_sign ? l_false : l_true;
VERIFY(legal_to_flip(v0));
m[v0] = var_sign ? l_false : l_true;
}
if (st) {
process_stack(m, clause, st->stack());
@ -115,11 +121,11 @@ namespace sat {
bool_var v = l.var();
if (v >= m.size()) std::cout << v << " model size: " << m.size() << "\n";
VERIFY(v < m.size());
if (v == it->var())
if (v == v0)
var_sign = sign;
if (value_at(l, m) == l_true)
sat = true;
else if (!sat && v != it->var() && m[v] == l_undef) {
else if (!sat && v != v0 && m[v] == l_undef) {
VERIFY(legal_to_flip(v));
// clause can be satisfied by assigning v.
m[v] = sign ? l_false : l_true;