mirror of
https://github.com/Z3Prover/z3
synced 2025-04-24 01:25:31 +00:00
add sorting-based pb encoding in the style of minisat+
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
c347018cb8
commit
dc588b54f7
3 changed files with 263 additions and 88 deletions
|
|
@ -33,6 +33,7 @@ namespace sat {
|
|||
literal_vector m_units;
|
||||
unsigned_vector m_units_lim;
|
||||
unsigned_vector m_learned_lim;
|
||||
unsigned_vector m_binary;
|
||||
|
||||
|
||||
void init() {
|
||||
|
|
@ -44,6 +45,7 @@ namespace sat {
|
|||
m_learned_lim.push_back(s.m_learned.size());
|
||||
m_units_lim.push_back(m_units.size());
|
||||
m_trail.push_back(lit);
|
||||
m_binary.push_back(0);
|
||||
s.push();
|
||||
assign(lit);
|
||||
}
|
||||
|
|
@ -58,27 +60,31 @@ namespace sat {
|
|||
s.m_cls_allocator.del_clause(r);
|
||||
}
|
||||
s.m_learned.shrink(old_sz);
|
||||
literal lits[2] = { m_trail.back(), null_literal };
|
||||
unsigned new_unit_sz = m_units_lim.back();
|
||||
for (unsigned i = m_units.size(); i > new_unit_sz; ) {
|
||||
--i;
|
||||
lits[1] = m_units[i];
|
||||
for (unsigned i = new_unit_sz; i < m_units.size(); ++i) {
|
||||
literal lits[2] = { ~m_trail.back(), m_units[i] };
|
||||
clause * r = s.m_cls_allocator.mk_clause(2, lits, true);
|
||||
s.m_learned.push_back(r);
|
||||
}
|
||||
m_units.shrink(new_unit_sz);
|
||||
m_units_lim.pop_back();
|
||||
m_trail.pop_back();
|
||||
m_binary.pop_back();
|
||||
}
|
||||
|
||||
unsigned diff(unsigned value0) const {
|
||||
unsigned value1 = get_state_value();
|
||||
SASSERT(value1 >= value0);
|
||||
return value1 - value0;
|
||||
unsigned diff() const { return m_binary.back() + m_units.size() - m_units_lim.back(); }
|
||||
|
||||
unsigned mix_diff(unsigned l, unsigned r) const { return l + r + (1 << 10) * l * r; }
|
||||
|
||||
clause const& get_clause(watch_list::iterator it) const {
|
||||
clause_offset cls_off = it->get_clause_offset();
|
||||
return *(s.m_cls_allocator.get_clause(cls_off));
|
||||
}
|
||||
|
||||
unsigned mix_diff(unsigned l, unsigned r) const {
|
||||
return l + r + (1 << 10) * l * r;
|
||||
bool is_nary_propagation(clause const& c, literal l) const {
|
||||
bool r = c.size() > 2 && ((c[0] == l && s.value(c[1]) == l_false) || (c[1] == l && s.value(c[0]) == l_false));
|
||||
DEBUG_CODE(if (r) for (unsigned j = 2; j < c.size(); ++j) SASSERT(s.value(c[j]) == l_false););
|
||||
return r;
|
||||
}
|
||||
|
||||
void get_resolvent_units(literal lit) {
|
||||
|
|
@ -94,34 +100,33 @@ namespace sat {
|
|||
switch (it->get_kind()) {
|
||||
case watched::TERNARY:
|
||||
if (s.value(it->get_literal1()) == l_false &&
|
||||
s.value(it->get_literal()) == l_false) {
|
||||
s.value(it->get_literal2()) == l_false) {
|
||||
m_units.push_back(l);
|
||||
goto done_watch_list;
|
||||
goto done_finding_unit;
|
||||
}
|
||||
break;
|
||||
case watched::CLAUSE: {
|
||||
clause_offset cls_off = it->get_clause_offset();
|
||||
clause & c = *(s.m_cls_allocator.get_clause(cls_off));
|
||||
if (c.size() == 2) break;
|
||||
SASSERT(c.size() > 2);
|
||||
if (c[0] == l && s.value(c[1]) == l_false) {
|
||||
DEBUG_CODE(for (unsigned j = 2; j < c.size(); ++j) SASSERT(s.value(c[j]) == l_false););
|
||||
clause const & c = get_clause(it);
|
||||
SASSERT(c[0] == l || c[1] == l);
|
||||
if (is_nary_propagation(c, l)) {
|
||||
m_units.push_back(l);
|
||||
goto done_watch_list;
|
||||
}
|
||||
if (c[1] == l && s.value(c[0]) == l_false) {
|
||||
DEBUG_CODE(for (unsigned j = 2; j < c.size(); ++j) SASSERT(s.value(c[j]) == l_false););
|
||||
m_units.push_back(l);
|
||||
goto done_watch_list;
|
||||
}
|
||||
goto done_finding_unit;
|
||||
}
|
||||
break;
|
||||
}
|
||||
default:
|
||||
break;
|
||||
}
|
||||
}
|
||||
done_watch_list:
|
||||
done_finding_unit:
|
||||
|
||||
//
|
||||
// TBD: count binary clauses created by propagation.
|
||||
// They used to be in the watch list of l.index(),
|
||||
// both new literals in watch list should be unassigned.
|
||||
//
|
||||
continue;
|
||||
|
||||
}
|
||||
}
|
||||
|
||||
|
|
@ -131,10 +136,6 @@ namespace sat {
|
|||
return l;
|
||||
}
|
||||
|
||||
unsigned get_state_value() const {
|
||||
return s.m_learned.size();
|
||||
}
|
||||
|
||||
bool choose1(literal& l) {
|
||||
literal_vector P;
|
||||
pre_select(P);
|
||||
|
|
@ -142,28 +143,26 @@ namespace sat {
|
|||
if (P.empty()) {
|
||||
return true;
|
||||
}
|
||||
unsigned value0 = get_state_value();
|
||||
unsigned h = 0, count = 1;
|
||||
literal_vector& units = m_units;;
|
||||
for (unsigned i = 0; i < P.size(); ++i) {
|
||||
literal lit = P[i];
|
||||
|
||||
push(lit);
|
||||
if (do_double(value0)) double_look();
|
||||
if (do_double()) double_look(P);
|
||||
if (inconsistent()) {
|
||||
pop();
|
||||
assign(~lit);
|
||||
if (do_double(value0)) double_look();
|
||||
if (do_double()) double_look(P);
|
||||
if (inconsistent()) return true;
|
||||
continue;
|
||||
}
|
||||
unsigned diff1 = diff(value0);
|
||||
unsigned diff1 = diff();
|
||||
pop();
|
||||
|
||||
push(~lit);
|
||||
if (do_double(value0)) double_look();
|
||||
if (do_double()) double_look(P);
|
||||
bool unsat2 = inconsistent();
|
||||
unsigned diff2 = diff(value0);
|
||||
unsigned diff2 = diff();
|
||||
pop();
|
||||
|
||||
if (unsat2) {
|
||||
|
|
@ -173,25 +172,28 @@ namespace sat {
|
|||
|
||||
unsigned mixd = mix_diff(diff1, diff2);
|
||||
|
||||
|
||||
if (mixd > h || (mixd == h && s.m_rand(count) == 0)) {
|
||||
CTRACE("sat", l != null_literal, tout << lit << " diff1: " << diff1 << " diff2: " << diff2 << "\n";);
|
||||
if (mixd > h) count = 1; else ++count;
|
||||
h = mixd;
|
||||
l = diff1 < diff2 ? lit : ~lit;
|
||||
++count;
|
||||
}
|
||||
}
|
||||
return l != null_literal;
|
||||
}
|
||||
|
||||
void double_look() {
|
||||
literal_vector P;
|
||||
pre_select(P);
|
||||
void double_look(literal_vector const& P) {
|
||||
bool unsat;
|
||||
for (unsigned i = 0; !inconsistent() && i < P.size(); ++i) {
|
||||
literal lit = P[i];
|
||||
if (s.value(lit) != l_undef) continue;
|
||||
|
||||
push(lit);
|
||||
bool unsat = inconsistent();
|
||||
unsat = inconsistent();
|
||||
pop();
|
||||
if (unsat) {
|
||||
TRACE("sat", tout << "unit: " << ~lit << "\n";);
|
||||
assign(~lit);
|
||||
continue;
|
||||
}
|
||||
|
|
@ -200,6 +202,7 @@ namespace sat {
|
|||
unsat = inconsistent();
|
||||
pop();
|
||||
if (unsat) {
|
||||
TRACE("sat", tout << "unit: " << lit << "\n";);
|
||||
assign(lit);
|
||||
}
|
||||
|
||||
|
|
@ -211,6 +214,7 @@ namespace sat {
|
|||
s.assign(l, justification());
|
||||
s.propagate(false);
|
||||
get_resolvent_units(l);
|
||||
TRACE("sat", s.display(tout << l << " @ " << s.scope_lvl() << " " << (inconsistent()?"unsat":"sat") << "\n"););
|
||||
}
|
||||
|
||||
bool inconsistent() { return s.inconsistent(); }
|
||||
|
|
@ -220,6 +224,18 @@ namespace sat {
|
|||
order_by_implication_trees(P);
|
||||
}
|
||||
|
||||
void check_binary(clause const& c, literal lit1, literal& lit2) {
|
||||
if (c.size() == 2) {
|
||||
if (c[0] == lit1) {
|
||||
lit2 = c[1];
|
||||
}
|
||||
else {
|
||||
SASSERT(c[1] == lit1);
|
||||
lit2 = c[0];
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
void order_by_implication_trees(literal_vector& P) {
|
||||
literal_set roots;
|
||||
literal_vector nodes, parent;
|
||||
|
|
@ -246,28 +262,19 @@ namespace sat {
|
|||
lit2 = it->get_literal();
|
||||
break;
|
||||
case watched::CLAUSE: {
|
||||
clause_offset cls_off = it->get_clause_offset();
|
||||
clause & c = *(s.m_cls_allocator.get_clause(cls_off));
|
||||
if (c.size() == 2) {
|
||||
if (c[0] == ~lit1) {
|
||||
lit2 = c[1];
|
||||
}
|
||||
else {
|
||||
SASSERT(c[1] == ~lit1);
|
||||
lit2 = c[0];
|
||||
}
|
||||
}
|
||||
clause const & c = get_clause(it);
|
||||
check_binary(c, lit1, lit2);
|
||||
break;
|
||||
}
|
||||
default:
|
||||
break;
|
||||
}
|
||||
|
||||
if (lit2 != null_literal && roots.contains(lit2)) {
|
||||
// lit2 => lit1
|
||||
if (lit2 != null_literal && roots.contains(~lit2)) {
|
||||
// ~lit2 => lit1
|
||||
// if lit2 is a root, put it under lit2
|
||||
parent.setx(lit2.index(), lit1, null_literal);
|
||||
roots.remove(lit2);
|
||||
parent.setx((~lit2).index(), lit1, null_literal);
|
||||
roots.remove(~lit2);
|
||||
roots.insert(lit1);
|
||||
goto found;
|
||||
}
|
||||
|
|
@ -287,17 +294,8 @@ namespace sat {
|
|||
lit2 = it->get_literal();
|
||||
break;
|
||||
case watched::CLAUSE: {
|
||||
clause_offset cls_off = it->get_clause_offset();
|
||||
clause & c = *(s.m_cls_allocator.get_clause(cls_off));
|
||||
if (c.size() == 2) {
|
||||
if (c[0] == lit1) {
|
||||
lit2 = c[1];
|
||||
}
|
||||
else {
|
||||
SASSERT(c[1] == lit1);
|
||||
lit2 = c[0];
|
||||
}
|
||||
}
|
||||
clause const & c = get_clause(it);
|
||||
check_binary(c, ~lit1, lit2);
|
||||
break;
|
||||
}
|
||||
default:
|
||||
|
|
@ -311,19 +309,21 @@ namespace sat {
|
|||
goto found;
|
||||
}
|
||||
}
|
||||
std::cout << "no parents or children of literal " << lit1 << "\n";
|
||||
nodes.push_back(lit1);
|
||||
roots.insert(lit1);
|
||||
found:
|
||||
;
|
||||
}
|
||||
std::cout << "implication trees\n";
|
||||
for (unsigned i = 0; i < parent.size(); ++i) {
|
||||
literal p = parent[i];
|
||||
if (p != null_literal) {
|
||||
std::cout << to_literal(i) << " |-> " << p << "\n";
|
||||
}
|
||||
}
|
||||
}
|
||||
TRACE("sat",
|
||||
tout << "implication trees\n";
|
||||
for (unsigned i = 0; i < parent.size(); ++i) {
|
||||
literal p = parent[i];
|
||||
if (p != null_literal) {
|
||||
tout << to_literal(i) << " |-> " << p << "\n";
|
||||
}
|
||||
});
|
||||
|
||||
// TBD: extract ordering.
|
||||
|
||||
}
|
||||
|
||||
|
|
@ -335,9 +335,8 @@ namespace sat {
|
|||
}
|
||||
}
|
||||
|
||||
bool do_double(unsigned value0) {
|
||||
unsigned value1 = get_state_value();
|
||||
return !inconsistent() && value1 - value0 > m_delta_trigger;
|
||||
bool do_double() {
|
||||
return !inconsistent() && diff() > m_delta_trigger;
|
||||
}
|
||||
|
||||
void update_delta_trigger() {
|
||||
|
|
@ -368,11 +367,11 @@ namespace sat {
|
|||
s.checkpoint();
|
||||
BACKTRACK;
|
||||
literal l = choose();
|
||||
TRACE("sat", tout << l << "\n";);
|
||||
BACKTRACK;
|
||||
if (l == null_literal) {
|
||||
return l_true;
|
||||
}
|
||||
TRACE("sat", tout << "choose: " << l << " " << trail << "\n";);
|
||||
push(l);
|
||||
trail.push_back(l);
|
||||
}
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue