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compress elimination stack representation

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-10-17 21:28:48 -07:00
parent e0e7836c12
commit 8811d78415
3 changed files with 108 additions and 54 deletions
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22
src/sat/sat_model_converter.cpp
View file

@ -38,16 +38,15 @@ namespace sat {
return *this; return *this;
} }
void model_converter::process_stack(model & m, literal_vector const& stack) const { void model_converter::process_stack(model & m, literal_vector const& c, elim_stackv const& stack) const {
SASSERT(!stack.empty()); SASSERT(!stack.empty());
unsigned sz = stack.size(); unsigned sz = stack.size();
SASSERT(stack[sz - 1] == null_literal); for (unsigned i = sz; i-- > 0; ) {
for (unsigned i = sz - 1; i-- > 0; ) { unsigned csz = stack[i].first;
literal lit = stack[i]; // this is the literal that is pivoted on. It is repeated literal lit = stack[i].second;
bool sat = false; bool sat = false;
for (; i > 0 && stack[--i] != null_literal;) { for (unsigned j = 0; !sat && j < csz; ++j) {
if (sat) continue; sat = value_at(c[j], m) == l_true;
sat = value_at(stack[i], m) == l_true;
} }
if (!sat) { if (!sat) {
m[lit.var()] = lit.sign() ? l_false : l_true; m[lit.var()] = lit.sign() ? l_false : l_true;
@ -66,6 +65,7 @@ namespace sat {
bool sat = false; bool sat = false;
bool var_sign = false; bool var_sign = false;
unsigned index = 0; unsigned index = 0;
literal_vector clause;
for (literal l : it->m_clauses) { for (literal l : it->m_clauses) {
if (l == null_literal) { if (l == null_literal) {
// end of clause // end of clause
@ -74,13 +74,15 @@ namespace sat {
} }
elim_stack* s = it->m_elim_stack[index]; elim_stack* s = it->m_elim_stack[index];
if (s) { if (s) {
process_stack(m, s->stack()); process_stack(m, clause, s->stack());
} }
sat = false; sat = false;
++index; ++index;
clause.reset();
continue; continue;
} }
clause.push_back(l);
if (sat) if (sat)
continue; continue;
bool sign = l.sign(); bool sign = l.sign();
@ -190,13 +192,13 @@ namespace sat {
// TRACE("sat_mc_bug", tout << "adding (wrapper): "; for (literal l : c) tout << l << " "; tout << "\n";); // 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) { void model_converter::insert(entry & e, literal_vector const& c, elim_stackv const& elims) {
SASSERT(c.contains(literal(e.var(), false)) || c.contains(literal(e.var(), true))); SASSERT(c.contains(literal(e.var(), false)) || c.contains(literal(e.var(), true)));
SASSERT(m_entries.begin() <= &e); SASSERT(m_entries.begin() <= &e);
SASSERT(&e < m_entries.end()); SASSERT(&e < m_entries.end());
for (literal l : c) e.m_clauses.push_back(l); for (literal l : c) e.m_clauses.push_back(l);
e.m_clauses.push_back(null_literal); e.m_clauses.push_back(null_literal);
e.m_elim_stack.push_back(alloc(elim_stack, elims)); e.m_elim_stack.push_back(elims.empty() ? nullptr : alloc(elim_stack, elims));
TRACE("sat_mc_bug", tout << "adding: " << c << "\n";); TRACE("sat_mc_bug", tout << "adding: " << c << "\n";);
} }

12
src/sat/sat_model_converter.h
View file

@ -39,18 +39,20 @@ namespace sat {
class model_converter { class model_converter {
public: public:
typedef svector<std::pair<unsigned, literal>> elim_stackv;
class elim_stack { class elim_stack {
unsigned m_refcount; unsigned m_refcount;
literal_vector m_stack; elim_stackv m_stack;
public: public:
elim_stack(literal_vector const& stack): elim_stack(elim_stackv const& stack):
m_refcount(0), m_refcount(0),
m_stack(stack) { m_stack(stack) {
} }
~elim_stack() { } ~elim_stack() { }
void inc_ref() { ++m_refcount; } void inc_ref() { ++m_refcount; }
void dec_ref() { if (0 == --m_refcount) dealloc(this); } void dec_ref() { if (0 == --m_refcount) dealloc(this); }
literal_vector const& stack() const { return m_stack; } elim_stackv const& stack() const { return m_stack; }
}; };
enum kind { ELIM_VAR = 0, BLOCK_LIT }; enum kind { ELIM_VAR = 0, BLOCK_LIT };
@ -74,7 +76,7 @@ namespace sat {
private: private:
vector<entry> m_entries; vector<entry> m_entries;
void process_stack(model & m, literal_vector const& stack) const; void process_stack(model & m, literal_vector const& clause, elim_stackv const& stack) const;
public: public:
model_converter(); model_converter();
@ -86,7 +88,7 @@ namespace sat {
void insert(entry & e, clause const & c); void insert(entry & e, clause const & c);
void insert(entry & e, literal l1, literal l2); void insert(entry & e, literal l1, literal l2);
void insert(entry & e, clause_wrapper const & c); void insert(entry & e, clause_wrapper const & c);
void insert(entry & c, literal_vector const& covered_clause, literal_vector const& elim_stack); void insert(entry & c, literal_vector const& covered_clause, elim_stackv const& elim_stack);
bool empty() const { return m_entries.empty(); } bool empty() const { return m_entries.empty(); }

128
src/sat/sat_simplifier.cpp
View file

@ -965,6 +965,7 @@ namespace sat {
literal l = m_queue.next(); literal l = m_queue.next();
process(l); process(l);
} }
cce();
} }
// //
@ -1027,55 +1028,106 @@ namespace sat {
literal_vector m_covered_clause; literal_vector m_covered_clause;
literal_vector m_intersection; literal_vector m_intersection;
literal_vector m_elim_stack; sat::model_converter::elim_stackv m_elim_stack;
unsigned m_ala_qhead;
bool cla(literal lit) { /*
* C \/ l l \/ lit
* -------------------
* C \/ l \/ ~lit
*/
void add_ala() {
for (; m_ala_qhead < m_covered_clause.size(); ++m_ala_qhead) {
literal l = m_covered_clause[m_ala_qhead];
for (watched & w : s.get_wlist(~l)) {
if (w.is_binary_clause()) {
literal lit = w.get_literal();
if (!s.is_marked(lit) && !s.is_marked(~lit)) {
//std::cout << "ALA " << ~lit << "\n";
m_covered_clause.push_back(~lit);
s.mark_visited(~lit);
}
}
}
}
}
bool add_cla(literal& blocked) {
for (unsigned i = 0; i < m_covered_clause.size(); ++i) {
m_intersection.reset();
if (ri(m_covered_clause[i], m_intersection)) {
blocked = m_covered_clause[i];
return true;
}
for (literal l : m_intersection) {
if (!s.is_marked(l)) {
s.mark_visited(l);
m_covered_clause.push_back(l);
}
}
if (!m_intersection.empty()) {
m_elim_stack.push_back(std::make_pair(m_covered_clause.size(), m_covered_clause[i]));
}
}
return false;
}
bool cla(literal& blocked) {
bool is_tautology = false; bool is_tautology = false;
for (literal l : m_covered_clause) s.mark_visited(l); for (literal l : m_covered_clause) s.mark_visited(l);
unsigned num_iterations = 0, sz; unsigned num_iterations = 0, sz;
m_elim_stack.reset(); m_elim_stack.reset();
m_ala_qhead = 0;
do { do {
++num_iterations; do {
sz = m_covered_clause.size(); ++num_iterations;
for (unsigned i = 0; i < m_covered_clause.size(); ++i) { sz = m_covered_clause.size();
m_intersection.reset(); is_tautology = add_cla(blocked);
if (ri(m_covered_clause[i], m_intersection) && m_covered_clause[i] == lit) {
is_tautology = true;
break;
}
for (literal l : m_intersection) {
if (!s.is_marked(l)) {
s.mark_visited(l);
m_covered_clause.push_back(l);
}
}
if (!m_intersection.empty()) {
m_elim_stack.append(m_covered_clause); // the current clause
m_elim_stack.push_back(m_covered_clause[i]); // the pivot literal
m_elim_stack.push_back(null_literal); // null demarcation
}
} }
while (m_covered_clause.size() > sz && !is_tautology);
break;
//if (is_tautology) break;
//sz = m_covered_clause.size();
// unsound? add_ala();
} }
while (m_covered_clause.size() > sz && !is_tautology); while (m_covered_clause.size() > sz);
for (literal l : m_covered_clause) s.unmark_visited(l); for (literal l : m_covered_clause) s.unmark_visited(l);
if (is_tautology) std::cout << "taut: " << num_iterations << "\n"; // if (is_tautology) std::cout << "taut: " << num_iterations << " " << m_covered_clause.size() << " " << m_elim_stack.size() << "\n";
return is_tautology; return is_tautology;
} }
// perform covered clause elimination. // perform covered clause elimination.
// first extract the covered literal addition (CLA). // first extract the covered literal addition (CLA).
// then check whether the CLA is blocked. // then check whether the CLA is blocked.
bool cce(clause& c, literal lit) { bool cce(clause& c, literal& blocked) {
m_covered_clause.reset(); m_covered_clause.reset();
for (literal l : c) m_covered_clause.push_back(l); for (literal l : c) m_covered_clause.push_back(l);
return cla(lit); return cla(blocked);
} }
bool cce(literal lit, literal l2) { bool cce(literal lit, literal l2, literal& blocked) {
m_covered_clause.reset(); m_covered_clause.reset();
m_covered_clause.push_back(lit); m_covered_clause.push_back(lit);
m_covered_clause.push_back(l2); m_covered_clause.push_back(l2);
return cla(lit); return cla(blocked);
}
void cce() {
m_to_remove.reset();
literal blocked;
for (clause* cp : s.s.m_clauses) {
clause& c = *cp;
if (c.was_removed()) continue;
if (cce(c, blocked)) {
model_converter::entry * new_entry = 0;
block_covered_clause(c, blocked, new_entry);
s.m_num_covered_clauses++;
}
}
for (clause* c : m_to_remove) {
s.remove_clause(*c);
}
m_to_remove.reset();
} }
void process(literal l) { void process(literal l) {
@ -1085,6 +1137,7 @@ namespace sat {
return; return;
} }
literal blocked = null_literal;
m_to_remove.reset(); m_to_remove.reset();
{ {
clause_use_list & occs = s.m_use_list.get(l); clause_use_list & occs = s.m_use_list.get(l);
@ -1095,14 +1148,10 @@ namespace sat {
SASSERT(c.contains(l)); SASSERT(c.contains(l));
s.mark_all_but(c, l); s.mark_all_but(c, l);
if (all_tautology(l)) { if (all_tautology(l)) {
s.unmark_all(c);
block_clause(c, l, new_entry); block_clause(c, l, new_entry);
s.m_num_blocked_clauses++; s.m_num_blocked_clauses++;
} }
else if (cce(c, l)) { s.unmark_all(c);
block_covered_clause(c, l, new_entry);
s.m_num_covered_clauses++;
}
it.next(); it.next();
} }
} }
@ -1127,8 +1176,9 @@ namespace sat {
block_binary(it, l, new_entry); block_binary(it, l, new_entry);
s.m_num_blocked_clauses++; s.m_num_blocked_clauses++;
} }
else if (cce(l, l2)) { else if (cce(l, l2, blocked)) {
block_covered_binary(it, l, new_entry); model_converter::entry * blocked_entry = 0;
block_covered_binary(it, l, blocked, blocked_entry);
s.m_num_covered_clauses++; s.m_num_covered_clauses++;
} }
else { else {
@ -1163,9 +1213,9 @@ namespace sat {
mc.insert(*new_entry, m_covered_clause, m_elim_stack); mc.insert(*new_entry, m_covered_clause, m_elim_stack);
} }
void prepare_block_binary(watch_list::iterator it, literal l, model_converter::entry *& new_entry) { void prepare_block_binary(watch_list::iterator it, literal l, literal blocked, model_converter::entry *& new_entry) {
if (new_entry == 0) if (new_entry == 0)
new_entry = &(mc.mk(model_converter::BLOCK_LIT, l.var())); new_entry = &(mc.mk(model_converter::BLOCK_LIT, blocked.var()));
literal l2 = it->get_literal(); literal l2 = it->get_literal();
TRACE("blocked_clause", tout << "new blocked clause: " << l2 << " " << l << "\n";); TRACE("blocked_clause", tout << "new blocked clause: " << l2 << " " << l << "\n";);
s.remove_bin_clause_half(l2, l, it->is_learned()); s.remove_bin_clause_half(l2, l, it->is_learned());
@ -1173,12 +1223,12 @@ namespace sat {
} }
void block_binary(watch_list::iterator it, literal l, model_converter::entry *& new_entry) { void block_binary(watch_list::iterator it, literal l, model_converter::entry *& new_entry) {
prepare_block_binary(it, l, new_entry); prepare_block_binary(it, l, l, new_entry);
mc.insert(*new_entry, l, it->get_literal()); mc.insert(*new_entry, l, it->get_literal());
} }
void block_covered_binary(watch_list::iterator it, literal l, model_converter::entry *& new_entry) { void block_covered_binary(watch_list::iterator it, literal l, literal blocked, model_converter::entry *& new_entry) {
prepare_block_binary(it, l, new_entry); prepare_block_binary(it, l, blocked, new_entry);
mc.insert(*new_entry, m_covered_clause, m_elim_stack); mc.insert(*new_entry, m_covered_clause, m_elim_stack);
} }