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fix bugs related to use of lookahead equivalences and encoding of pb constraints

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-05-15 09:33:27 -07:00
parent c49550ff2d
commit 2033e649b5
8 changed files with 115 additions and 70 deletions
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94
src/sat/card_extension.cpp
View file

@ -482,7 +482,7 @@ namespace sat {
}
}
void card_extension::display(std::ostream& out, pb& p, bool values) const {
void card_extension::display(std::ostream& out, pb const& p, bool values) const {
out << p.lit() << "[" << p.size() << "]";
if (p.lit() != null_literal && values) {
out << "@(" << value(p.lit());
@ -835,8 +835,9 @@ namespace sat {
bool card_extension::resolve_conflict() {
if (0 == m_num_propagations_since_pop)
if (0 == m_num_propagations_since_pop) {
return false;
}
reset_coeffs();
m_num_marks = 0;
m_bound = 0;
@ -941,6 +942,7 @@ namespace sat {
m_bound += offset;
inc_coeff(consequent, offset);
get_pb_antecedents(consequent, p, m_lemma);
TRACE("sat", tout << m_lemma << "\n";);
for (unsigned i = 0; i < m_lemma.size(); ++i) {
process_antecedent(~m_lemma[i], offset);
}
@ -1187,6 +1189,7 @@ namespace sat {
void card_extension::add_at_least(bool_var v, literal_vector const& lits, unsigned k) {
unsigned index = 4*m_cards.size();
SASSERT(is_card_index(index));
literal lit = v == null_bool_var ? null_literal : literal(v, false);
card* c = new (memory::allocate(card::get_obj_size(lits.size()))) card(index, lit, lits, k);
m_cards.push_back(c);
@ -1203,7 +1206,8 @@ namespace sat {
}
void card_extension::add_pb_ge(bool_var v, svector<wliteral> const& wlits, unsigned k) {
unsigned index = 4*m_pbs.size() + 0x11;
unsigned index = 4*m_pbs.size() + 0x3;
SASSERT(is_pb_index(index));
literal lit = v == null_bool_var ? null_literal : literal(v, false);
pb* p = new (memory::allocate(pb::get_obj_size(wlits.size()))) pb(index, lit, wlits, k);
m_pbs.push_back(p);
@ -1221,7 +1225,8 @@ namespace sat {
void card_extension::add_xor(bool_var v, literal_vector const& lits) {
m_has_xor = true;
unsigned index = 4*m_xors.size() + 0x01;
unsigned index = 4*m_xors.size() + 0x1;
SASSERT(is_xor_index(index));
xor* x = new (memory::allocate(xor::get_obj_size(lits.size()))) xor(index, literal(v, false), lits);
m_xors.push_back(x);
init_watch(v);
@ -1358,46 +1363,50 @@ namespace sat {
SASSERT(max_sum < k);
}
void card_extension::get_card_antecedents(literal l, card const& c, literal_vector& r) {
DEBUG_CODE(
bool found = false;
for (unsigned i = 0; !found && i < c.k(); ++i) {
found = c[i] == l;
}
SASSERT(found););
if (c.lit() != null_literal) r.push_back(c.lit());
SASSERT(c.lit() == null_literal || value(c.lit()) == l_true);
for (unsigned i = c.k(); i < c.size(); ++i) {
SASSERT(value(c[i]) == l_false);
r.push_back(~c[i]);
}
}
void card_extension::get_xor_antecedents(literal l, xor const& x, literal_vector& r) {
if (x.lit() != null_literal) r.push_back(x.lit());
// TRACE("sat", display(tout << l << " ", x, true););
SASSERT(x.lit() == null_literal || value(x.lit()) == l_true);
SASSERT(x[0].var() == l.var() || x[1].var() == l.var());
if (x[0].var() == l.var()) {
SASSERT(value(x[1]) != l_undef);
r.push_back(value(x[1]) == l_true ? x[1] : ~x[1]);
}
else {
SASSERT(value(x[0]) != l_undef);
r.push_back(value(x[0]) == l_true ? x[0] : ~x[0]);
}
for (unsigned i = 2; i < x.size(); ++i) {
SASSERT(value(x[i]) != l_undef);
r.push_back(value(x[i]) == l_true ? x[i] : ~x[i]);
}
}
void card_extension::get_antecedents(literal l, ext_justification_idx idx, literal_vector & r) {
if (is_card_index(idx)) {
card& c = index2card(idx);
DEBUG_CODE(
bool found = false;
for (unsigned i = 0; !found && i < c.k(); ++i) {
found = c[i] == l;
}
SASSERT(found););
if (c.lit() != null_literal) r.push_back(c.lit());
SASSERT(c.lit() == null_literal || value(c.lit()) == l_true);
for (unsigned i = c.k(); i < c.size(); ++i) {
SASSERT(value(c[i]) == l_false);
r.push_back(~c[i]);
}
get_card_antecedents(l, index2card(idx), r);
}
else if (is_xor_index(idx)) {
xor& x = index2xor(idx);
if (x.lit() != null_literal) r.push_back(x.lit());
TRACE("sat", display(tout << l << " ", x, true););
SASSERT(x.lit() == null_literal || value(x.lit()) == l_true);
SASSERT(x[0].var() == l.var() || x[1].var() == l.var());
if (x[0].var() == l.var()) {
SASSERT(value(x[1]) != l_undef);
r.push_back(value(x[1]) == l_true ? x[1] : ~x[1]);
}
else {
SASSERT(value(x[0]) != l_undef);
r.push_back(value(x[0]) == l_true ? x[0] : ~x[0]);
}
for (unsigned i = 2; i < x.size(); ++i) {
SASSERT(value(x[i]) != l_undef);
r.push_back(value(x[i]) == l_true ? x[i] : ~x[i]);
}
get_xor_antecedents(l, index2xor(idx), r);
}
else if (is_pb_index(idx)) {
pb const& p = index2pb(idx);
get_pb_antecedents(l, p, r);
get_pb_antecedents(l, index2pb(idx), r);
}
else {
UNREACHABLE();
@ -1635,7 +1644,7 @@ namespace sat {
out << ">= " << ineq.m_k << "\n";
}
void card_extension::display(std::ostream& out, xor& x, bool values) const {
void card_extension::display(std::ostream& out, xor const& x, bool values) const {
out << "xor " << x.lit();
if (x.lit() != null_literal && values) {
out << "@(" << value(x.lit());
@ -1664,7 +1673,7 @@ namespace sat {
out << "\n";
}
void card_extension::display(std::ostream& out, card& c, bool values) const {
void card_extension::display(std::ostream& out, card const& c, bool values) const {
out << c.lit() << "[" << c.size() << "]";
if (c.lit() != null_literal && values) {
out << "@(" << value(c.lit());
@ -1728,10 +1737,7 @@ namespace sat {
pb& p = index2pb(idx);
out << "pb " << p.lit() << ": ";
for (unsigned i = 0; i < p.size(); ++i) {
if (p[i].first != 1) {
out << p[i].first << " ";
}
out << p[i].second << " ";
out << p[i].first << "*" << p[i].second << " ";
}
out << ">= " << p.k();
}

19
src/sat/card_extension.h
View file

@ -74,7 +74,7 @@ namespace sat {
unsigned m_max_sum;
wliteral m_wlits[0];
public:
static size_t get_obj_size(unsigned num_lits) { return sizeof(card) + num_lits * sizeof(wliteral); }
static size_t get_obj_size(unsigned num_lits) { return sizeof(pb) + num_lits * sizeof(wliteral); }
pb(unsigned index, literal lit, svector<wliteral> const& wlits, unsigned k);
unsigned index() const { return m_index; }
literal lit() const { return m_lit; }
@ -205,6 +205,8 @@ namespace sat {
void reset_coeffs();
void reset_marked_literals();
void unwatch_literal(literal w, card* c);
void get_card_antecedents(literal l, card const& c, literal_vector & r);
// xor specific functionality
void copy_xor(card_extension& result);
@ -218,13 +220,14 @@ namespace sat {
lbool add_assign(xor& x, literal alit);
void asserted_xor(literal l, ptr_vector<xor>* xors, xor* x);
void get_xor_antecedents(literal l, unsigned index, justification js, literal_vector& r);
void get_xor_antecedents(literal l, xor const& x, literal_vector & r);
bool is_card_index(unsigned idx) const { return 0x00 == (idx & 0x11); }
bool is_xor_index(unsigned idx) const { return 0x01 == (idx & 0x11); }
bool is_pb_index(unsigned idx) const { return 0x11 == (idx & 0x11); }
bool is_card_index(unsigned idx) const { return 0x0 == (idx & 0x3); }
bool is_xor_index(unsigned idx) const { return 0x1 == (idx & 0x3); }
bool is_pb_index(unsigned idx) const { return 0x3 == (idx & 0x3); }
card& index2card(unsigned idx) const { SASSERT(is_card_index(idx)); return *m_cards[idx >> 2]; }
xor& index2xor(unsigned idx) const { SASSERT(!is_card_index(idx)); return *m_xors[idx >> 2]; }
xor& index2xor(unsigned idx) const { SASSERT(is_xor_index(idx)); return *m_xors[idx >> 2]; }
pb& index2pb(unsigned idx) const { SASSERT(is_pb_index(idx)); return *m_pbs[idx >> 2]; }
@ -285,9 +288,9 @@ namespace sat {
bool validate_resolvent();
void display(std::ostream& out, ineq& p) const;
void display(std::ostream& out, card& c, bool values) const;
void display(std::ostream& out, pb& p, bool values) const;
void display(std::ostream& out, xor& c, bool values) const;
void display(std::ostream& out, card const& c, bool values) const;
void display(std::ostream& out, pb const& p, bool values) const;
void display(std::ostream& out, xor const& c, bool values) const;
void display_watch(std::ostream& out, bool_var v) const;
void display_watch(std::ostream& out, bool_var v, bool sign) const;

4
src/sat/sat_config.cpp
View file

@ -38,6 +38,7 @@ namespace sat {
m_num_threads = 1;
m_local_search = 0;
m_lookahead_search = false;
m_lookahead_simplify = false;
m_ccc = false;
updt_params(p);
}
@ -83,7 +84,8 @@ namespace sat {
m_max_conflicts = p.max_conflicts();
m_num_threads = p.threads();
m_local_search = p.local_search();
m_local_search_threads = p.local_search_threads();
m_local_search_threads = p.local_search_threads();
m_lookahead_simplify = p.lookahead_simplify();
m_lookahead_search = p.lookahead_search();
m_ccc = p.ccc();

1
src/sat/sat_config.h
View file

@ -61,6 +61,7 @@ namespace sat {
unsigned m_local_search_threads;
bool m_local_search;
bool m_lookahead_search;
bool m_lookahead_simplify;
bool m_ccc;
unsigned m_simplify_mult1;

49
src/sat/sat_lookahead.h
View file

@ -251,19 +251,16 @@ namespace sat {
void del_binary(unsigned idx) {
// TRACE("sat", display(tout << "Delete " << to_literal(idx) << "\n"););
literal_vector & lits = m_binary[idx];
if (lits.empty()) IF_VERBOSE(0, verbose_stream() << "empty literals\n";);
SASSERT(!lits.empty());
literal l = lits.back();
lits.pop_back();
if (m_binary[(~l).index()].back() != ~to_literal(idx)) {
IF_VERBOSE(0, verbose_stream() << "pop bad literal: " << idx << " " << (~l).index() << "\n";);
}
if (m_binary[(~l).index()].empty())
IF_VERBOSE(0, verbose_stream() << "empty binary\n";);
lits.pop_back();
SASSERT(!m_binary[(~l).index()].empty());
IF_VERBOSE(0, if (m_binary[(~l).index()].back() != ~to_literal(idx)) verbose_stream() << "pop bad literal: " << idx << " " << (~l).index() << "\n";);
SASSERT(m_binary[(~l).index()].back() == ~to_literal(idx));
m_binary[(~l).index()].pop_back();
++m_stats.m_del_binary;
}
void validate_binary(literal l1, literal l2) {
if (m_search_mode == lookahead_mode::searching) {
m_assumptions.push_back(l1);
@ -1856,6 +1853,9 @@ namespace sat {
return search();
}
/**
\brief simplify set of clauses by extracting units from a lookahead at base level.
*/
void simplify() {
SASSERT(m_prefix == 0);
SASSERT(m_watches.empty());
@ -1875,12 +1875,38 @@ namespace sat {
++num_units;
}
}
IF_VERBOSE(1, verbose_stream() << "units found: " << num_units << "\n";);
IF_VERBOSE(1, verbose_stream() << "(sat-lookahead :units " << num_units << ")\n";);
m_s.m_simplifier.subsume();
m_lookahead.reset();
}
//
// there can be two sets of equivalence classes.
// example:
// a -> !b
// b -> !a
// c -> !a
// we pick as root the Boolean variable with the largest value.
//
literal get_root(bool_var v) {
literal lit(v, false);
literal r1 = get_parent(lit);
literal r2 = get_parent(literal(r1.var(), false));
CTRACE("sat", r1 != get_parent(literal(r2.var(), false)),
tout << r1 << " " << r2 << "\n";);
SASSERT(r1.var() == get_parent(literal(r2.var(), false)).var());
if (r1.var() >= r2.var()) {
return r1;
}
else {
return r1.sign() ? ~r2 : r2;
}
}
/**
\brief extract equivalence classes of variables and simplify clauses using these.
*/
void scc() {
SASSERT(m_prefix == 0);
SASSERT(m_watches.empty());
@ -1901,14 +1927,13 @@ namespace sat {
}
for (unsigned i = 0; i < m_candidates.size(); ++i) {
bool_var v = m_candidates[i].m_var;
literal lit = literal(v, false);
literal p = get_parent(lit);
literal p = get_root(v);
if (p != null_literal && p.var() != v && !m_s.is_external(v) && !m_s.was_eliminated(v) && !m_s.was_eliminated(p.var())) {
to_elim.push_back(v);
roots[v] = p;
}
}
IF_VERBOSE(1, verbose_stream() << "eliminate " << to_elim.size() << " variables\n";);
IF_VERBOSE(1, verbose_stream() << "(sat-lookahead :equivalences " << to_elim.size() << ")\n";);
elim_eqs elim(m_s);
elim(roots, to_elim);
}

1
src/sat/sat_params.pyg
View file

@ -32,5 +32,6 @@ def_module_params('sat',
('local_search_threads', UINT, 0, 'number of local search threads to find satisfiable solution'),
('local_search', BOOL, False, 'use local search instead of CDCL'),
('lookahead_search', BOOL, False, 'use lookahead solver'),
('lookahead_simplify', BOOL, False, 'use lookahead solver during simplification'),
('ccc', BOOL, False, 'use Concurrent Cube and Conquer solver')
))

11
src/sat/sat_simplifier.cpp
View file

@ -207,10 +207,6 @@ namespace sat {
}
while (!m_sub_todo.empty());
if (!learned) {
// perform lookahead simplification
lookahead(s).simplify();
}
bool vars_eliminated = m_num_elim_vars > m_old_num_elim_vars;
@ -228,6 +224,13 @@ namespace sat {
}
}
if (!learned && s.m_config.m_lookahead_simplify) {
// perform lookahead simplification
lookahead lh(s);
lh.simplify();
lh.collect_statistics(s.m_aux_stats);
}
CASSERT("sat_solver", s.check_invariant());
TRACE("after_simplifier", s.display(tout); tout << "model_converter:\n"; s.m_mc.display(tout););
finalize();

6
src/sat/sat_solver.cpp
View file

@ -1341,7 +1341,11 @@ namespace sat {
CASSERT("sat_simplify_bug", check_invariant());
}
lookahead(*this).scc();
if (m_config.m_lookahead_simplify) {
lookahead lh(*this);
lh.scc();
lh.collect_statistics(m_aux_stats);
}
sort_watch_lits();
CASSERT("sat_simplify_bug", check_invariant());