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add elimination stack for model reconstruction

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-10-17 04:52:06 -07:00
parent da4e8118b2
commit 42e9a0156b
4 changed files with 145 additions and 59 deletions
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60
src/sat/sat_model_converter.cpp
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@ -38,6 +38,22 @@ namespace sat {
return *this;
}
void model_converter::process_stack(model & m, literal_vector const& stack) const {
SASSERT(!stack.empty());
unsigned sz = stack.size();
SASSERT(stack[sz - 1] == null_literal);
for (unsigned i = sz - 1; i-- > 0; ) {
literal lit = stack[i]; // this is the literal that is pivoted on. It is repeated
bool sat = false;
for (; i > 0 && stack[--i] != null_literal;) {
if (sat) continue;
sat = value_at(stack[i], m) == l_true;
}
if (!sat) {
m[lit.var()] = lit.sign() ? l_false : l_true;
}
}
}
void model_converter::operator()(model & m) const {
vector<entry>::const_iterator begin = m_entries.begin();
@ -50,34 +66,20 @@ namespace sat {
bool sat = false;
bool var_sign = false;
unsigned index = 0;
literal prev = null_literal;
for (literal l : it->m_clauses) {
if (l == null_literal) {
// end of clause
if (!sat && it->m_elim_sequence[index]) {
SASSERT(prev != null_literal);
m[prev.var()] = prev.sign() ? l_false : l_true;
elim_sequence* s = it->m_elim_sequence[index];
#if 0
while (!sat) {
SASSERT(s);
for (literal l2 : s->clause()) {
sat = value_at(l2, m) == l_true;
}
s->clause();
}
#endif
NOT_IMPLEMENTED_YET();
}
if (!sat) {
m[it->var()] = var_sign ? l_false : l_true;
break;
}
elim_stack* s = it->m_elim_stack[index];
if (s) {
process_stack(m, s->stack());
}
sat = false;
++index;
continue;
continue;
}
prev = l;
if (sat)
continue;
@ -155,17 +157,16 @@ namespace sat {
return e;
}
void model_converter::insert(entry & e, clause const & c, elim_sequence* s) {
void model_converter::insert(entry & e, clause const & c) {
SASSERT(c.contains(e.var()));
SASSERT(m_entries.begin() <= &e);
SASSERT(&e < m_entries.end());
for (literal l : c) e.m_clauses.push_back(l);
e.m_clauses.push_back(null_literal);
e.m_elim_sequence.push_back(s);
e.m_elim_stack.push_back(nullptr);
TRACE("sat_mc_bug", tout << "adding: " << c << "\n";);
}
void model_converter::insert(entry & e, literal l1, literal l2) {
SASSERT(l1.var() == e.var() || l2.var() == e.var());
SASSERT(m_entries.begin() <= &e);
@ -173,7 +174,7 @@ namespace sat {
e.m_clauses.push_back(l1);
e.m_clauses.push_back(l2);
e.m_clauses.push_back(null_literal);
e.m_elim_sequence.push_back(nullptr);
e.m_elim_stack.push_back(nullptr);
TRACE("sat_mc_bug", tout << "adding (binary): " << l1 << " " << l2 << "\n";);
}
@ -185,10 +186,21 @@ namespace sat {
for (unsigned i = 0; i < sz; ++i)
e.m_clauses.push_back(c[i]);
e.m_clauses.push_back(null_literal);
e.m_elim_sequence.push_back(nullptr);
e.m_elim_stack.push_back(nullptr);
// TRACE("sat_mc_bug", tout << "adding (wrapper): "; for (literal l : c) tout << l << " "; tout << "\n";);
}
void model_converter::insert(entry & e, literal_vector const& c, literal_vector const& elims) {
SASSERT(c.contains(literal(e.var(), false)) || c.contains(literal(e.var(), true)));
SASSERT(m_entries.begin() <= &e);
SASSERT(&e < m_entries.end());
for (literal l : c) e.m_clauses.push_back(l);
e.m_clauses.push_back(null_literal);
e.m_elim_stack.push_back(alloc(elim_stack, elims));
TRACE("sat_mc_bug", tout << "adding: " << c << "\n";);
}
bool model_converter::check_invariant(unsigned num_vars) const {
// After a variable v occurs in an entry n and the entry has kind ELIM_VAR,
// then the variable must not occur in any other entry occurring after it.