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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-07-06 22:12:18 -07:00
parent da263601e6
commit 53c38f02d5
5 changed files with 340 additions and 169 deletions
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448
src/sat/ba_solver.cpp
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@ -94,6 +94,7 @@ namespace sat {
bool ba_solver::pb_base::well_formed() const {
uint_set vars;
if (lit() != null_literal) vars.insert(lit().var());
for (unsigned i = 0; i < size(); ++i) {
bool_var v = get_lit(i).var();
if (vars.contains(v)) return false;
@ -149,6 +150,7 @@ namespace sat {
for (unsigned i = 0; i < size(); ++i) {
m_wlits[i].first = std::min(k(), m_wlits[i].first);
if (m_max_sum + m_wlits[i].first < m_max_sum) {
std::cout << "update-max-sum overflows\n";
throw default_exception("addition of pb coefficients overflows");
}
m_max_sum += m_wlits[i].first;
@ -200,10 +202,11 @@ namespace sat {
bool ba_solver::xor::well_formed() const {
uint_set vars;
if (lit() != null_literal) vars.insert(lit().var());
for (literal l : *this) {
bool_var v = l.var();
if (vars.contains(v)) return false;
vars.insert(v);
vars.insert(v);
}
return true;
}
@ -326,6 +329,8 @@ namespace sat {
// pb
static unsigned _bad_id = 11111111; // 2759; //
#define BADLOG(_cmd_) if (p.id() == _bad_id) { _cmd_; }
// watch a prefix of literals, such that the slack of these is >= k
bool ba_solver::init_watch(pb& p, bool is_true) {
@ -354,9 +359,8 @@ namespace sat {
++j;
}
}
if (p.id() == _bad_id) {
std::cout << "watch " << num_watch << " out of " << sz << "\n";
}
BADLOG(std::cout << "watch " << num_watch << " out of " << sz << "\n");
DEBUG_CODE(
bool is_false = false;
for (unsigned k = 0; k < sz; ++k) {
@ -383,14 +387,14 @@ namespace sat {
p.set_slack(slack);
p.set_num_watch(num_watch);
validate_watch(p);
SASSERT(validate_watch(p));
TRACE("sat", display(tout << "init watch: ", p, true););
// slack is tight:
if (slack + slack1 == bound) {
SASSERT(slack1 == 0);
SASSERT(j == num_watch);
SASSERT(j == num_watch);
for (unsigned i = 0; i < j; ++i) {
assign(p, p[i].second);
}
@ -412,11 +416,11 @@ namespace sat {
Sw += a_s
Lw = Lw u {l_s}
Lu = Lu \ {l_s}
}
if (Sw < k) return conflict
for (li in Lw | Sw < k + ai)
}
if (Sw < k) return conflict
for (li in Lw | Sw < k + ai)
assign li
return no-conflict
return no-conflict
a_max index: index of non-false literal with maximal weight.
*/
@ -428,10 +432,7 @@ namespace sat {
m_a_max = p[index].first;
}
}
}
#define BADLOG(_cmd_) if (p.id() == _bad_id) { _cmd_; }
}
/*
\brief propagate assignment to alit in constraint p.
@ -465,7 +466,7 @@ namespace sat {
}
add_index(p, index, lit);
}
if (index == num_watch) {
if (index == num_watch || num_watch == 0) {
_bad_id = p.id();
std::cout << "BAD: " << p.id() << "\n";
display(std::cout, p, true);
@ -493,9 +494,7 @@ namespace sat {
literal lit = p[j].second;
if (value(lit) != l_false) {
slack += p[j].first;
if (is_watched(p[j].second, p)) {
std::cout << "Swap literal already watched: " << p[j].second << "\n";
}
SASSERT(!is_watched(p[j].second, p));
watch_literal(p[j], p);
p.swap(num_watch, j);
add_index(p, num_watch, lit);
@ -519,11 +518,10 @@ namespace sat {
set_conflict(p, alit);
return l_false;
}
if (index > p.size() || num_watch > p.size() || num_watch == 0 || p.id() == _bad_id) {
display(std::cout, p, true);
std::cout << "size: " << p.size() << " index: " << index << " num watch: " << num_watch << "\n";
}
if (num_watch == 1) { _bad_id = p.id(); }
BADLOG(std::cout << "size: " << p.size() << " index: " << index << " num watch: " << num_watch << "\n");
// swap out the watched literal.
--num_watch;
@ -532,6 +530,7 @@ namespace sat {
p.set_num_watch(num_watch);
p.swap(num_watch, index);
//
// slack >= bound, but slack - w(l) < bound
// l must be true.
@ -564,12 +563,10 @@ namespace sat {
}
void ba_solver::clear_watch(pb& p) {
validate_watch(p);
for (unsigned i = 0; i < p.num_watch(); ++i) {
unwatch_literal(p[i].second, p);
}
p.set_num_watch(0);
validate_watch(p);
}
/*
@ -687,10 +684,10 @@ namespace sat {
--i;
}
}
if (p.id() == _bad_id) display(std::cout << "simplify ", p, true);
BADLOG(display(std::cout << "simplify ", p, true));
p.set_size(sz);
p.set_k(p.k() - true_val);
if (p.id() == _bad_id) display(std::cout << "simplified ", p, true);
BADLOG(display(std::cout << "simplified ", p, true));
// display(verbose_stream(), c, true);
if (p.k() == 1 && p.lit() == null_literal) {
@ -876,45 +873,69 @@ namespace sat {
m_active_vars.shrink(j);
}
void ba_solver::inc_coeff(literal l, int offset) {
void ba_solver::inc_coeff(literal l, int64 offset) {
SASSERT(offset > 0);
bool_var v = l.var();
SASSERT(v != null_bool_var);
if (static_cast<bool_var>(m_coeffs.size()) <= v) {
m_coeffs.resize(v + 1, 0);
}
int coeff0 = m_coeffs[v];
int64 coeff0 = m_coeffs[v];
if (coeff0 == 0) {
m_active_vars.push_back(v);
}
int inc = l.sign() ? -offset : offset;
int coeff1 = inc + coeff0;
int64 inc = l.sign() ? -offset : offset;
int64 coeff1 = inc + coeff0;
m_coeffs[v] = coeff1;
if (coeff1 > INT_MAX || coeff1 < INT_MIN) {
std::cout << "overflow update coefficient " << coeff1 << "\n";
m_overflow = true;
return;
}
if (coeff0 > 0 && inc < 0) {
m_bound -= coeff0 - std::max(0, coeff1);
m_bound -= coeff0 - std::max(0LL, coeff1);
}
else if (coeff0 < 0 && inc > 0) {
m_bound -= std::min(0, coeff1) - coeff0;
m_bound -= std::min(0LL, coeff1) - coeff0;
}
// reduce coefficient to be no larger than bound.
if (coeff1 > m_bound) {
m_coeffs[v] = m_bound;
}
else if (coeff1 < 0 && -coeff1 > m_bound) {
m_coeffs[v] = -m_bound;
m_coeffs[v] = m_bound;
}
}
int ba_solver::get_coeff(bool_var v) const {
int64 ba_solver::get_coeff(bool_var v) const {
return m_coeffs.get(v, 0);
}
int ba_solver::get_abs_coeff(bool_var v) const {
int64 ba_solver::get_abs_coeff(bool_var v) const {
return abs(get_coeff(v));
}
int ba_solver::get_int_coeff(bool_var v) const {
int64 c = m_coeffs.get(v, 0);
if (c < INT_MIN || c > INT_MAX) {
std::cout << "overflow " << c << "\n";
m_overflow = true;
return 0;
}
return static_cast<int>(c);
}
unsigned ba_solver::get_bound() const {
if (m_bound < 0 || m_bound > UINT_MAX) {
std::cout << "overflow bound " << m_bound << "\n";
m_overflow = true;
return 1;
}
return static_cast<unsigned>(m_bound);
}
void ba_solver::reset_coeffs() {
for (unsigned i = 0; i < m_active_vars.size(); ++i) {
m_coeffs[m_active_vars[i]] = 0;
@ -923,11 +944,14 @@ namespace sat {
}
static bool _debug_conflict = false;
static literal _debug_consequent = null_literal;
static unsigned_vector _debug_var2position;
lbool ba_solver::resolve_conflict() {
if (0 == m_num_propagations_since_pop) {
return l_undef;
}
m_overflow = false;
reset_coeffs();
m_num_marks = 0;
m_bound = 0;
@ -941,25 +965,25 @@ namespace sat {
}
literal_vector const& lits = s().m_trail;
unsigned idx = lits.size() - 1;
int offset = 1;
int64 offset = 1;
DEBUG_CODE(active2pb(m_A););
unsigned init_marks = m_num_marks;
do {
if (offset == 0) {
goto process_next_resolvent;
}
// TBD: need proper check for overflow.
if (offset > (1 << 12)) {
IF_VERBOSE(12, verbose_stream() << "offset: " << offset << "\n";
if (m_overflow || offset > (1 << 12)) {
IF_VERBOSE(20, verbose_stream() << "offset: " << offset << "\n";
active2pb(m_A);
display(verbose_stream(), m_A);
);
goto bail_out;
}
if (offset == 0) {
goto process_next_resolvent;
}
TRACE("sat_verbose", display(tout, m_A););
TRACE("sat", tout << "process consequent: " << consequent << ":\n"; s().display_justification(tout, js) << "\n";);
SASSERT(offset > 0);
@ -971,6 +995,7 @@ namespace sat {
std::cout << consequent << "\n";
s().display_justification(std::cout, js);
std::cout << "\n";
_debug_consequent = consequent;
}
switch(js.get_kind()) {
case justification::NONE:
@ -1056,7 +1081,6 @@ namespace sat {
SASSERT(validate_lemma());
DEBUG_CODE(
active2pb(m_C);
//SASSERT(validate_resolvent());
@ -1096,7 +1120,6 @@ namespace sat {
DEBUG_CODE(active2pb(m_A););
}
SASSERT(value(consequent) == l_true);
}
while (m_num_marks > 0);
@ -1111,6 +1134,10 @@ namespace sat {
active2card();
if (m_overflow) {
goto bail_out;
}
SASSERT(validate_conflict(m_lemma, m_A));
TRACE("sat", tout << m_lemma << "\n";);
@ -1130,6 +1157,9 @@ namespace sat {
return l_true;
bail_out:
m_overflow = false;
while (m_num_marks > 0 && idx >= 0) {
bool_var v = lits[idx].var();
if (s().is_marked(v)) {
@ -1138,11 +1168,20 @@ namespace sat {
}
if (idx == 0 && !_debug_conflict) {
_debug_conflict = true;
_debug_var2position.reserve(s().num_vars());
for (unsigned i = 0; i < lits.size(); ++i) {
_debug_var2position[lits[i].var()] = i;
}
// s().display(std::cout);
std::cout << s().m_not_l << "\n";
active2pb(m_A);
uint64 c = 0;
for (uint64 c1 : m_A.m_coeffs) c += c1;
std::cout << "sum of coefficients: " << c << "\n";
display(std::cout, m_A, true);
std::cout << "conflicting literal: " << s().m_not_l << "\n";
for (literal l : lits) {
if (s().is_marked(l.var())) {
std::cout << "missing mark: " << l << "\n";
IF_VERBOSE(0, verbose_stream() << "missing mark: " << l << "\n";);
s().reset_mark(l.var());
}
}
@ -1158,7 +1197,7 @@ namespace sat {
adjust_conflict_level:
int slack = -m_bound;
int64 slack = -m_bound;
for (bool_var v : m_active_vars) {
slack += get_abs_coeff(v);
}
@ -1166,10 +1205,10 @@ namespace sat {
m_lemma.reset();
m_lemma.push_back(null_literal);
unsigned num_skipped = 0;
int asserting_coeff = 0;
for (unsigned i = 0; /* 0 <= slack && */ i < m_active_vars.size(); ++i) {
int64 asserting_coeff = 0;
for (unsigned i = 0; 0 <= slack && i < m_active_vars.size(); ++i) {
bool_var v = m_active_vars[i];
int coeff = get_coeff(v);
int64 coeff = get_coeff(v);
lbool val = value(v);
bool is_true = val == l_true;
bool append = coeff != 0 && val != l_undef && (coeff < 0 == is_true);
@ -1216,38 +1255,30 @@ namespace sat {
IF_VERBOSE(10, verbose_stream() << "(sat.backjump :new-level " << m_conflict_lvl << " :old-level " << old_level << ")\n";);
goto adjust_conflict_level;
}
// slack is related to coefficients of m_lemma
// so does not apply to unit coefficients.
// std::cout << "lemma: " << m_lemma << " >= " << 1 << "\n";
// active2pb(m_A);
// display(std::cout, m_A, true);
#if 0
constraint* c = active2constraint();
if (c) {
display(std::cout, *c, true);
std::cout << "Eval: " << eval(*c) << "\n";
}
#endif
return true;
}
/*
\brief compute a cut for current resolvent.
*/
void ba_solver::cut() {
unsigned g = 0;
int sum_of_units = 0;
// bypass cut if there is a unit coefficient
for (bool_var v : m_active_vars) {
if (1 == get_abs_coeff(v) && ++sum_of_units >= m_bound) return;
if (1 == get_abs_coeff(v)) return;
}
//active2pb(m_A);
//display(std::cout << "units can be removed\n", m_A, true);
SASSERT(0 <= m_bound && m_bound <= UINT_MAX);
unsigned g = 0;
for (unsigned i = 0; g != 1 && i < m_active_vars.size(); ++i) {
bool_var v = m_active_vars[i];
int coeff = get_abs_coeff(v);
int64 coeff = get_abs_coeff(v);
if (coeff == 0) {
continue;
}
if (coeff == 1) return;
if (m_bound < coeff) {
if (get_coeff(v) > 0) {
m_coeffs[v] = m_bound;
@ -1265,23 +1296,18 @@ namespace sat {
g = u_gcd(g, static_cast<unsigned>(coeff));
}
}
if (g >= 2) {
active2pb(m_A);
//display(std::cout, m_A, true);
normalize_active_coeffs();
int ig = static_cast<int>(g);
for (unsigned i = 0; i < m_active_vars.size(); ++i) {
m_coeffs[m_active_vars[i]] /= ig;
for (bool_var v : m_active_vars) {
m_coeffs[v] /= static_cast<int>(g);
}
m_bound = (m_bound + g - 1) / g;
++m_stats.m_num_cut;
//std::cout << "CUT " << g << "\n";
//active2pb(m_A);
//display(std::cout, m_A, true);
}
}
void ba_solver::process_card(card& c, int offset) {
void ba_solver::process_card(card& c, int64 offset) {
literal lit = c.lit();
SASSERT(c.k() <= c.size());
SASSERT(lit == null_literal || value(lit) == l_true);
@ -1297,7 +1323,7 @@ namespace sat {
}
}
void ba_solver::process_antecedent(literal l, int offset) {
void ba_solver::process_antecedent(literal l, int64 offset) {
SASSERT(value(l) == l_false);
bool_var v = l.var();
unsigned level = lvl(v);
@ -1306,6 +1332,9 @@ namespace sat {
s().mark(v);
TRACE("sat", tout << "Mark: v" << v << "\n";);
++m_num_marks;
if (_debug_conflict && _debug_consequent != null_literal && _debug_var2position[_debug_consequent.var()] < _debug_var2position[l.var()]) {
std::cout << "antecedent " << l << " is above consequent in stack\n";
}
}
inc_coeff(l, offset);
}
@ -1359,9 +1388,6 @@ namespace sat {
}
void ba_solver::add_constraint(constraint* c) {
if (c->id() == _bad_id) {
display(std::cout, *c, true);
}
if (c->learned()) {
m_learned.push_back(c);
}
@ -1463,6 +1489,50 @@ namespace sat {
}
}
double ba_solver::get_reward(card const& c, literal_occs_fun& literal_occs) const {
unsigned k = c.k(), slack = 0;
double to_add = 0;
for (literal l : c) {
switch (value(l)) {
case l_true: --k; if (k == 0) return 0; break;
case l_undef: to_add += literal_occs(l); ++slack; break;
case l_false: break;
}
}
if (k >= slack) return 1;
return pow(0.5, slack - k + 1) * to_add;
}
double ba_solver::get_reward(pb const& c, literal_occs_fun& occs) const {
unsigned k = c.k(), slack = 0;
double to_add = 0;
double undefs = 0;
for (wliteral wl : c) {
literal l = wl.second;
unsigned w = wl.first;
switch (value(l)) {
case l_true: if (k <= w) return 0; k -= w; break;
case l_undef: to_add += occs(l); ++undefs; slack += w; break; // TBD multiplier factor on this
case l_false: break;
}
}
if (k >= slack || 0 == undefs) return 0;
double avg = slack / undefs;
return pow(0.5, (slack - k + 1)/avg) * to_add;
}
double ba_solver::get_reward(literal l, ext_justification_idx idx, literal_occs_fun& occs) const {
constraint const& c = index2constraint(idx);
unsigned sz = c.size();
switch (c.tag()) {
case card_t: return get_reward(c.to_card(), occs);
case pb_t: return get_reward(c.to_pb(), occs);
case xor_t: return 0;
default: UNREACHABLE(); return 0;
}
}
void ba_solver::ensure_parity_size(bool_var v) {
if (m_parity_marks.size() <= static_cast<unsigned>(v)) {
@ -1585,6 +1655,11 @@ namespace sat {
unsigned k = p.k();
if (_debug_conflict) {
display(std::cout, p, true);
std::cout << "literal: " << l << " value: " << value(l) << " num-watch: " << p.num_watch() << " slack: " << p.slack() << "\n";
}
if (value(l) == l_false) {
// The literal comes from a conflict.
// it is forced true, but assigned to false.
@ -1619,6 +1694,10 @@ namespace sat {
CTRACE("sat", coeff == 0, display(tout << l << " coeff: " << coeff << "\n", p, true););
if (_debug_conflict) {
std::cout << "coeff " << coeff << "\n";
}
SASSERT(coeff > 0);
unsigned slack = p.slack() - coeff;
@ -1688,20 +1767,10 @@ namespace sat {
}
void ba_solver::unwatch_literal(literal lit, constraint& c) {
if (c.id() == _bad_id) { std::cout << "unwatch " << lit << "\n"; }
get_wlist(~lit).erase(watched(c.index()));
if (is_watched(lit, c)) {
std::cout << "Not deleted " << lit << "\n";
}
}
void ba_solver::watch_literal(literal lit, constraint& c) {
if (is_watched(lit, c)) {
std::cout << "Already watched " << lit << "\n";
UNREACHABLE();
exit(0);
}
if (c.id() == _bad_id) { std::cout << "watch " << lit << "\n"; }
get_wlist(~lit).push_back(watched(c.index()));
}
@ -1867,9 +1936,7 @@ namespace sat {
if (c.lit() != null_literal && value(c.lit()) != l_true) return true;
if (c.lit() != null_literal && lvl(c.lit()) != 0) {
if (!is_watched(c.lit(), c) || !is_watched(~c.lit(), c)) {
std::cout << "Definition literal is not watched " << c.lit() << " " << c << "\n";
display_watch_list(std::cout, s().m_cls_allocator, get_wlist(c.lit())) << "\n";
display_watch_list(std::cout, s().m_cls_allocator, get_wlist(~c.lit())) << "\n";
UNREACHABLE();
return false;
}
}
@ -1882,12 +1949,15 @@ namespace sat {
bool found = is_watched(l, c);
if (found != c.is_watching(l)) {
std::cout << "Discrepancy of watched literal: " << l << " id: " << c.id() << " clause: " << c << (found?" is watched, but shouldn't be":" not watched, but should be") << "\n";
display_watch_list(std::cout << l << ": ", s().m_cls_allocator, get_wlist(l)) << "\n";
display_watch_list(std::cout << ~l << ": ", s().m_cls_allocator, get_wlist(~l)) << "\n";
std::cout << "value: " << value(l) << " level: " << lvl(l) << "\n";
display(std::cout, c, true);
if (c.lit() != null_literal) std::cout << value(c.lit()) << "\n";
IF_VERBOSE(0,
verbose_stream() << "Discrepancy of watched literal: " << l << " id: " << c.id()
<< " clause: " << c << (found?" is watched, but shouldn't be":" not watched, but should be") << "\n";
display_watch_list(verbose_stream() << l << ": ", s().m_cls_allocator, get_wlist(l)) << "\n";
display_watch_list(verbose_stream() << ~l << ": ", s().m_cls_allocator, get_wlist(~l)) << "\n";
verbose_stream() << "value: " << value(l) << " level: " << lvl(l) << "\n";
display(verbose_stream(), c, true);
if (c.lit() != null_literal) verbose_stream() << value(c.lit()) << "\n";);
UNREACHABLE();
exit(1);
return false;
@ -1900,8 +1970,6 @@ namespace sat {
for (unsigned i = 0; i < p.size(); ++i) {
literal l = p[i].second;
if (lvl(l) != 0 && is_watched(l, p) != i < p.num_watch()) {
std::cout << "DISCREPANCY: " << l << " at " << i << " for " << p.num_watch() << " index: " << p.id() << "\n";
display(std::cout, p, true);
UNREACHABLE();
return false;
}
@ -2067,13 +2135,14 @@ namespace sat {
m_simplify_change = false;
m_clause_removed = false;
m_constraint_removed = false;
for (constraint* c : m_constraints) simplify(*c);
for (constraint* c : m_learned) simplify(*c);
for (unsigned sz = m_constraints.size(), i = 0; i < sz; ++i) simplify(*m_constraints[i]);
for (unsigned sz = m_learned.size(), i = 0; i < sz; ++i) simplify(*m_learned[i]);
init_use_lists();
remove_unused_defs();
set_non_external();
elim_pure();
subsumption();
for (unsigned sz = m_constraints.size(), i = 0; i < sz; ++i) subsumption(*m_constraints[i]);
for (unsigned sz = m_learned.size(), i = 0; i < sz; ++i) subsumption(*m_learned[i]);
cleanup_clauses();
cleanup_constraints();
}
@ -2242,12 +2311,10 @@ namespace sat {
m_visited.resize(s().num_vars()*2, false);
m_constraint_removed = false;
for (constraint* c : m_constraints) {
flush_roots(*c);
}
for (constraint* c : m_learned) {
flush_roots(*c);
}
for (unsigned sz = m_constraints.size(), i = 0; i < sz; ++i)
flush_roots(*m_constraints[i]);
for (unsigned sz = m_learned.size(), i = 0; i < sz; ++i)
flush_roots(*m_learned[i]);
cleanup_constraints();
// validate();
@ -2342,7 +2409,7 @@ namespace sat {
}
literal root = c.lit();
remove_constraint(c);
constraint* p = add_pb_ge(root, wlits, k, c.learned());
add_pb_ge(root, wlits, k, c.learned());
}
else {
if (c.lit() == null_literal || value(c.lit()) == l_true) {
@ -2644,11 +2711,29 @@ namespace sat {
unsigned ext = 0;
for (unsigned v = 0; v < s().num_vars(); ++v) {
literal lit(v, false);
if (s().is_external(v) && m_cnstr_use_list[lit.index()].size() == 0 && m_cnstr_use_list[(~lit).index()].size() == 0 && !s().is_assumption(v)) {
if (s().is_external(v) &&
m_cnstr_use_list[lit.index()].size() == 0 &&
m_cnstr_use_list[(~lit).index()].size() == 0 && !s().is_assumption(v)) {
s().set_non_external(v);
++ext;
}
}
// ensure that lemmas use only external variables.
for (constraint* cp : m_learned) {
constraint& c = *cp;
if (c.was_removed()) continue;
SASSERT(c.lit() == null_literal);
for (unsigned i = 0; i < c.size(); ++i) {
bool_var v = c.get_lit(i).var();
if (s().was_eliminated(v)) {
remove_constraint(c);
break;
}
if (!s().is_external(v)) {
s().set_external(v);
}
}
}
IF_VERBOSE(10, verbose_stream() << "non-external variables converted: " << ext << "\n";);
return ext;
}
@ -2680,11 +2765,6 @@ namespace sat {
return pure_literals;
}
void ba_solver::subsumption() {
for (constraint* c : m_constraints) subsumption(*c);
for (constraint* c : m_learned) subsumption(*c);
}
void ba_solver::subsumption(constraint& cnstr) {
if (cnstr.was_removed()) return;
switch (cnstr.tag()) {
@ -2693,6 +2773,11 @@ namespace sat {
if (c.k() > 1) subsumption(c);
break;
}
case pb_t: {
pb& p = cnstr.to_pb();
if (p.k() > 1) subsumption(p);
break;
}
default:
break;
}
@ -2805,6 +2890,45 @@ namespace sat {
return c1_exclusive + 1 <= c1.k();
}
/*
\brief Ax >= k subsumes By >= k' if
all coefficients in A are <= B and k >= k'
*/
bool ba_solver::subsumes(pb const& p1, pb_base const& p2) {
if (p1.k() < p2.k()) return false;
unsigned num_marked = 0;
for (unsigned i = 0; i < p2.size(); ++i) {
literal l = p2.get_lit(i);
if (is_marked(l)) {
++num_marked;
if (m_weights[l.index()] > p2.get_coeff(i)) return false;
}
}
return num_marked == p1.size();
}
void ba_solver::subsumes(pb& p1, literal lit) {
for (constraint* c : m_cnstr_use_list[lit.index()]) {
if (c == &p1 || c->was_removed()) continue;
bool s = false;
switch (c->tag()) {
case card_t:
s = subsumes(p1, c->to_card());
break;
case pb_t:
s = subsumes(p1, c->to_pb());
break;
default:
break;
}
if (s) {
++m_stats.m_num_card_subsumes;
p1.set_learned(false);
remove_constraint(*c);
}
}
}
literal ba_solver::get_min_occurrence_literal(card const& c) {
unsigned occ_count = UINT_MAX;
literal lit = null_literal;
@ -2821,7 +2945,7 @@ namespace sat {
void ba_solver::card_subsumption(card& c1, literal lit) {
literal_vector slit;
for (constraint* c : m_cnstr_use_list[lit.index()]) {
if (!c || c->tag() != card_t || c == &c1 || c->was_removed()) {
if (!c->is_card() || c == &c1 || c->was_removed()) {
continue;
}
card& c2 = c->to_card();
@ -2910,8 +3034,7 @@ namespace sat {
}
void ba_solver::subsumption(card& c1) {
SASSERT(!c1.was_removed());
if (c1.lit() != null_literal) {
if (c1.was_removed() || c1.lit() != null_literal) {
return;
}
clause_vector removed_clauses;
@ -2930,6 +3053,24 @@ namespace sat {
}
}
void ba_solver::subsumption(pb& p1) {
if (p1.was_removed() || p1.lit() != null_literal) {
return;
}
for (wliteral l : p1) {
mark_visited(l.second);
SASSERT(m_weights[l.second.index()] == 0);
m_weights[l.second.index()] = l.first;
}
for (unsigned i = 0; i < p1.num_watch(); ++i) {
subsumes(p1, p1[i].second);
}
for (wliteral l : p1) {
unmark_visited(l.second);
m_weights[l.second.index()] = 0;
}
}
void ba_solver::clauses_modifed() {}
lbool ba_solver::get_phase(bool_var v) { return l_undef; }
@ -3145,11 +3286,11 @@ namespace sat {
}
bool ba_solver::validate_lemma() {
int val = -m_bound;
int64 val = -m_bound;
reset_active_var_set();
for (bool_var v : m_active_vars) {
if (m_active_var_set.contains(v)) continue;
int coeff = get_coeff(v);
int64 coeff = get_coeff(v);
if (coeff == 0) continue;
m_active_var_set.insert(v);
literal lit(v, false);
@ -3173,7 +3314,7 @@ namespace sat {
p.reset(m_bound);
for (bool_var v : m_active_vars) {
if (m_active_var_set.contains(v)) continue;
int coeff = get_coeff(v);
int64 coeff = get_coeff(v);
if (coeff == 0) continue;
m_active_var_set.insert(v);
literal lit(v, coeff < 0);
@ -3184,32 +3325,27 @@ namespace sat {
ba_solver::constraint* ba_solver::active2constraint() {
reset_active_var_set();
literal_vector lits;
unsigned_vector coeffs;
bool all_one = true;
svector<wliteral> wlits;
uint64_t sum = 0;
if (m_bound == 1) return 0;
if (m_overflow) return 0;
for (bool_var v : m_active_vars) {
int coeff = get_coeff(v);
int coeff = get_int_coeff(v);
if (m_active_var_set.contains(v) || coeff == 0) continue;
m_active_var_set.insert(v);
literal lit(v, coeff < 0);
lits.push_back(lit);
coeffs.push_back(abs(coeff));
all_one &= abs(coeff) == 1;
wlits.push_back(wliteral(abs(coeff), lit));
sum += abs(coeff);
}
if (sum >= UINT_MAX/2) return 0;
if (all_one) {
return add_at_least(null_literal, lits, m_bound, true);
unsigned k = get_bound();
if (m_overflow || sum >= UINT_MAX/2) {
return 0;
}
else {
svector<wliteral> wlits;
for (unsigned i = 0; i < lits.size(); ++i) {
wlits.push_back(wliteral(coeffs[i], lits[i]));
}
return add_pb_ge(null_literal, wlits, m_bound, true);
}
return add_pb_ge(null_literal, wlits, k, true);
}
}
/*
@ -3247,7 +3383,7 @@ namespace sat {
normalize_active_coeffs();
svector<wliteral> wlits;
for (bool_var v : m_active_vars) {
int coeff = get_coeff(v);
int coeff = get_int_coeff(v);
wlits.push_back(std::make_pair(abs(coeff), literal(v, coeff < 0)));
}
std::sort(wlits.begin(), wlits.end(), compare_wlit());
@ -3264,7 +3400,7 @@ namespace sat {
}
while (!wlits.empty()) {
wliteral wl = wlits.back();
if (wl.first + sum0 >= static_cast<unsigned>(m_bound)) break;
if (wl.first + sum0 >= get_bound()) break;
wlits.pop_back();
sum0 += wl.first;
}
@ -3283,9 +3419,15 @@ namespace sat {
++num_max_level;
}
}
if (m_overflow) return 0;
if (slack >= k) {
#if 0
return active2constraint();
active2pb(m_A);
std::cout << "not asserting\n";
display(std::cout, m_A, true);
#endif
return 0;
}
@ -3374,15 +3516,15 @@ namespace sat {
// validate that m_A & m_B implies m_C
bool ba_solver::validate_resolvent() {
u_map<unsigned> coeffs;
unsigned k = m_A.m_k + m_B.m_k;
u_map<uint64> coeffs;
uint64 k = m_A.m_k + m_B.m_k;
for (unsigned i = 0; i < m_A.m_lits.size(); ++i) {
unsigned coeff = m_A.m_coeffs[i];
uint64 coeff = m_A.m_coeffs[i];
SASSERT(!coeffs.contains(m_A.m_lits[i].index()));
coeffs.insert(m_A.m_lits[i].index(), coeff);
}
for (unsigned i = 0; i < m_B.m_lits.size(); ++i) {
unsigned coeff1 = m_B.m_coeffs[i], coeff2;
uint64 coeff1 = m_B.m_coeffs[i], coeff2;
literal lit = m_B.m_lits[i];
if (coeffs.find((~lit).index(), coeff2)) {
if (coeff1 == coeff2) {
@ -3410,7 +3552,7 @@ namespace sat {
// C is above the sum of A and B
for (unsigned i = 0; i < m_C.m_lits.size(); ++i) {
literal lit = m_C.m_lits[i];
unsigned coeff;
uint64 coeff;
if (coeffs.find(lit.index(), coeff)) {
if (coeff > m_C.m_coeffs[i] && m_C.m_coeffs[i] < m_C.m_k) {
IF_VERBOSE(0, verbose_stream() << i << ": " << m_C.m_coeffs[i] << " " << m_C.m_k << "\n";);
@ -3444,9 +3586,9 @@ namespace sat {
return false;
}
}
unsigned value = 0;
uint64 value = 0;
for (unsigned i = 0; i < p.m_lits.size(); ++i) {
unsigned coeff = p.m_coeffs[i];
uint64 coeff = p.m_coeffs[i];
if (!lits.contains(p.m_lits[i])) {
value += coeff;
}

31
src/sat/ba_solver.h
View file

@ -191,9 +191,9 @@ namespace sat {
struct ineq {
literal_vector m_lits;
unsigned_vector m_coeffs;
unsigned m_k;
void reset(unsigned k) { m_lits.reset(); m_coeffs.reset(); m_k = k; }
svector<uint64> m_coeffs;
uint64 m_k;
void reset(uint64 k) { m_lits.reset(); m_coeffs.reset(); m_k = k; }
void push(literal l, unsigned c) { m_lits.push_back(l); m_coeffs.push_back(c); }
};
@ -213,9 +213,9 @@ namespace sat {
// conflict resolution
unsigned m_num_marks;
unsigned m_conflict_lvl;
svector<int> m_coeffs;
svector<int64> m_coeffs;
svector<bool_var> m_active_vars;
int m_bound;
int64 m_bound;
tracked_uint_set m_active_var_set;
literal_vector m_lemma;
literal_vector m_skipped;
@ -246,6 +246,9 @@ namespace sat {
bool subsumes(card& c1, card& c2, literal_vector& comp);
bool subsumes(card& c1, clause& c2, literal_vector& comp);
bool subsumed(card& c1, literal l1, literal l2);
bool subsumes(pb const& p1, pb_base const& p2);
void subsumes(pb& p1, literal lit);
void subsumption(pb& p1);
void binary_subsumption(card& c1, literal lit);
void clause_subsumption(card& c1, literal lit, clause_vector& removed_clauses);
void card_subsumption(card& c1, literal lit);
@ -259,7 +262,6 @@ namespace sat {
unsigned set_non_external();
unsigned elim_pure();
bool elim_pure(literal lit);
void subsumption();
void subsumption(constraint& c1);
void subsumption(card& c1);
void gc_half(char const* _method);
@ -317,6 +319,8 @@ namespace sat {
void flush_roots(card& c);
void recompile(card& c);
lbool eval(card const& c) const;
double get_reward(card const& c, literal_occs_fun& occs) const;
// xor specific functionality
void clear_watch(xor& x);
@ -343,6 +347,7 @@ namespace sat {
void flush_roots(pb& p);
void recompile(pb& p);
lbool eval(pb const& p) const;
double get_reward(pb const& p, literal_occs_fun& occs) const;
// access solver
inline lbool value(bool_var v) const { return value(literal(v, false)); }
@ -358,15 +363,18 @@ namespace sat {
inline void drat_add(literal_vector const& c, svector<drat::premise> const& premises) { m_solver->m_drat.add(c, premises); }
mutable bool m_overflow;
void reset_active_var_set();
void normalize_active_coeffs();
void inc_coeff(literal l, int offset);
int get_coeff(bool_var v) const;
int get_abs_coeff(bool_var v) const;
void inc_coeff(literal l, int64 offset);
int64 get_coeff(bool_var v) const;
int64 get_abs_coeff(bool_var v) const;
int get_int_coeff(bool_var v) const;
unsigned get_bound() const;
literal get_asserting_literal(literal conseq);
void process_antecedent(literal l, int offset);
void process_card(card& c, int offset);
void process_antecedent(literal l, int64 offset);
void process_card(card& c, int64 offset);
void cut();
bool create_asserting_lemma();
@ -432,6 +440,7 @@ namespace sat {
virtual void find_mutexes(literal_vector& lits, vector<literal_vector> & mutexes);
virtual void pop_reinit();
virtual void gc();
virtual double get_reward(literal l, ext_justification_idx idx, literal_occs_fun& occs) const;
ptr_vector<constraint> const & constraints() const { return m_constraints; }

7
src/sat/sat_extension.h
View file

@ -29,12 +29,19 @@ namespace sat {
CR_DONE, CR_CONTINUE, CR_GIVEUP
};
class literal_occs_fun {
public:
virtual double operator()(literal l) = 0;
};
class extension {
public:
virtual ~extension() {}
virtual void set_solver(solver* s) = 0;
virtual void set_lookahead(lookahead* s) = 0;
virtual bool propagate(literal l, ext_constraint_idx idx) = 0;
virtual double get_reward(literal l, ext_constraint_idx idx, literal_occs_fun& occs) const = 0;
virtual void get_antecedents(literal l, ext_justification_idx idx, literal_vector & r) = 0;
virtual void asserted(literal l) = 0;
virtual check_result check() = 0;

18
src/sat/sat_lookahead.cpp
View file

@ -852,6 +852,8 @@ namespace sat {
copy_clauses(m_s.m_clauses);
copy_clauses(m_s.m_learned);
m_config.m_use_ternary_reward &= !m_s.m_ext;
// copy units
unsigned trail_sz = m_s.init_trail_size();
for (unsigned i = 0; i < trail_sz; ++i) {
@ -883,12 +885,10 @@ namespace sat {
for (; it != end; ++it) {
clause& c = *(*it);
if (c.was_removed()) continue;
#if 0
// enable when there is a non-ternary reward system.
if (c.size() > 3) {
m_config.m_use_ternary_reward = false;
}
#endif
bool was_eliminated = false;
for (unsigned i = 0; !was_eliminated && i < c.size(); ++i) {
was_eliminated = m_s.was_eliminated(c[i].var());
@ -1042,6 +1042,14 @@ namespace sat {
// Only the size indicator needs to be updated on backtracking.
//
class lookahead_literal_occs_fun : public literal_occs_fun {
lookahead& lh;
public:
lookahead_literal_occs_fun(lookahead& lh): lh(lh) {}
double operator()(literal l) { return lh.literal_occs(l); }
};
void lookahead::propagate_clauses(literal l) {
SASSERT(is_true(l));
if (inconsistent()) return;
@ -1172,6 +1180,10 @@ namespace sat {
case watched::EXT_CONSTRAINT: {
SASSERT(m_s.m_ext);
bool keep = m_s.m_ext->propagate(l, it->get_ext_constraint_idx());
if (m_search_mode == lookahead_mode::lookahead1) {
lookahead_literal_occs_fun literal_occs_fn(*this);
m_lookahead_reward += m_s.m_ext->get_reward(l, it->get_ext_constraint_idx(), literal_occs_fn);
}
if (m_inconsistent) {
if (!keep) ++it;
set_conflict();
@ -1222,7 +1234,7 @@ namespace sat {
to_add += literal_occs(l);
}
}
m_lookahead_reward += pow(sz, -2) * to_add;
m_lookahead_reward += pow(0.5, sz) * to_add;
}
else {
m_lookahead_reward = (double)0.001;

5
src/sat/sat_lookahead.h
View file

@ -402,8 +402,7 @@ namespace sat {
literal select_literal();
void update_binary_clause_reward(literal l1, literal l2);
void update_nary_clause_reward(clause const& c);
double literal_occs(literal l);
void set_lookahead_reward(literal l, double f) { m_lits[l.index()].m_lookahead_reward = f; }
void inc_lookahead_reward(literal l, double f) { m_lits[l.index()].m_lookahead_reward += f; }
double get_lookahead_reward(literal l) const { return m_lits[l.index()].m_lookahead_reward; }
@ -486,6 +485,8 @@ namespace sat {
model const& get_model();
void collect_statistics(statistics& st) const;
double literal_occs(literal l);
};
}