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enable incremental consequence finding with restart timeout

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-01-02 10:07:02 -08:00
parent a4d5c4a00a
commit 74d3de01b3
4 changed files with 141 additions and 30 deletions
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2
src/sat/sat_params.pyg
View file

@ -7,7 +7,7 @@ def_module_params('sat',
('phase.caching.off', UINT, 100, 'phase caching off period (in number of conflicts)'),
('restart', SYMBOL, 'luby', 'restart strategy: luby or geometric'),
('restart.initial', UINT, 100, 'initial restart (number of conflicts)'),
('restart.max', UINT, 0, 'maximal number of restarts. Ignored if set to 0'),
('restart.max', UINT, UINT_MAX, 'maximal number of restarts.'),
('restart.factor', DOUBLE, 1.5, 'restart increment factor for geometric strategy'),
('random_freq', DOUBLE, 0.01, 'frequency of random case splits'),
('random_seed', UINT, 0, 'random seed'),

146
src/sat/sat_solver.cpp
View file

@ -768,7 +768,7 @@ namespace sat {
if (check_inconsistent()) return l_false;
gc();
if (m_config.m_restart_max != 0 && m_config.m_restart_max <= m_restarts) {
if (m_config.m_restart_max <= m_restarts) {
IF_VERBOSE(SAT_VB_LVL, verbose_stream() << "(sat \"abort: max-restarts\")\n";);
return l_undef;
}
@ -3122,6 +3122,9 @@ namespace sat {
literal_vector lits;
lbool is_sat = l_true;
if (m_config.m_restart_max != UINT_MAX && !m_model_is_current) {
return get_bounded_consequences(asms, vars, conseq);
}
if (!m_model_is_current) {
is_sat = check(asms.size(), asms.c_ptr());
}
@ -3142,9 +3145,89 @@ namespace sat {
return is_sat;
}
void solver::fixup_consequence_core() {
index_set s;
for (unsigned i = 0; i < m_core.size(); ++i) {
s |= m_antecedents.find(m_core[i].var());
}
m_core.reset();
index_set::iterator it = s.begin(), end = s.end();
for (; it != end; ++it) {
m_core.push_back(to_literal(*it));
}
}
lbool solver::get_bounded_consequences(literal_vector const& asms, bool_var_vector const& vars, vector<literal_vector>& conseq) {
bool_var_set unfixed_vars;
unsigned num_units = 0, num_iterations = 0;
for (unsigned i = 0; i < vars.size(); ++i) {
unfixed_vars.insert(vars[i]);
}
m_antecedents.reset();
pop_to_base_level();
if (inconsistent()) return l_false;
init_search();
propagate(false);
if (inconsistent()) return l_false;
if (asms.empty()) {
bool_var v = mk_var(true, false);
literal lit(v, false);
init_assumptions(1, &lit, 0, 0);
}
else {
init_assumptions(asms.size(), asms.c_ptr(), 0, 0);
}
propagate(false);
if (check_inconsistent()) return l_false;
extract_fixed_consequences(num_units, asms, unfixed_vars, conseq);
simplify_problem();
if (check_inconsistent()) {
fixup_consequence_core();
return l_false;
}
while (true) {
++num_iterations;
SASSERT(!inconsistent());
lbool r = bounded_search();
if (r != l_undef) {
fixup_consequence_core();
return r;
}
extract_fixed_consequences(num_units, asms, unfixed_vars, conseq);
if (m_conflicts > m_config.m_max_conflicts) {
IF_VERBOSE(SAT_VB_LVL, verbose_stream() << "(sat \"abort: max-conflicts = " << m_conflicts << "\")\n";);
return l_undef;
}
restart();
simplify_problem();
if (check_inconsistent()) {
fixup_consequence_core();
return l_false;
}
gc();
if (m_config.m_restart_max <= num_iterations) {
IF_VERBOSE(SAT_VB_LVL, verbose_stream() << "(sat \"abort: max-restarts\")\n";);
return l_undef;
}
}
}
lbool solver::get_consequences(literal_vector const& asms, literal_vector const& lits, vector<literal_vector>& conseq) {
m_antecedents.reset();
literal_set vars(lits), assumptions(asms);
literal_set unfixed_lits(lits), assumptions(asms);
bool_var_set unfixed_vars;
for (unsigned i = 0; i < lits.size(); ++i) {
unfixed_vars.insert(lits[i].var());
}
pop_to_base_level();
if (inconsistent()) return l_false;
@ -3163,11 +3246,15 @@ namespace sat {
if (check_inconsistent()) return l_false;
unsigned num_units = 0, num_iterations = 0;
extract_fixed_consequences(num_units, assumptions, vars, conseq);
while (!vars.empty()) {
extract_fixed_consequences(num_units, assumptions, unfixed_vars, conseq);
update_unfixed_literals(unfixed_lits, unfixed_vars);
while (!unfixed_lits.empty()) {
if (scope_lvl() > 1) {
pop(scope_lvl() - 1);
}
++num_iterations;
checkpoint();
literal_set::iterator it = vars.begin(), end = vars.end();
literal_set::iterator it = unfixed_lits.begin(), end = unfixed_lits.end();
unsigned num_resolves = 0;
lbool is_sat = l_true;
for (; it != end; ++it) {
@ -3208,45 +3295,58 @@ namespace sat {
m_inconsistent = false;
}
if (is_sat == l_true) {
delete_unfixed(vars);
delete_unfixed(unfixed_lits, unfixed_vars);
}
extract_fixed_consequences(num_units, assumptions, vars, conseq);
extract_fixed_consequences(num_units, assumptions, unfixed_vars, conseq);
update_unfixed_literals(unfixed_lits, unfixed_vars);
IF_VERBOSE(1, verbose_stream() << "(sat.get-consequences"
<< " iterations: " << num_iterations
<< " variables: " << vars.size()
<< " variables: " << unfixed_lits.size()
<< " fixed: " << conseq.size()
<< " unfixed: " << lits.size() - conseq.size() - vars.size()
<< " unfixed: " << lits.size() - conseq.size() - unfixed_lits.size()
<< ")\n";);
if (!vars.empty() &&
m_config.m_restart_max != 0 &&
m_config.m_restart_max <= num_iterations) {
if (!unfixed_lits.empty() && m_config.m_restart_max <= num_iterations) {
return l_undef;
}
}
return l_true;
}
void solver::delete_unfixed(literal_set& unfixed) {
void solver::delete_unfixed(literal_set& unfixed_lits, bool_var_set& unfixed_vars) {
literal_set to_keep;
literal_set::iterator it = unfixed.begin(), end = unfixed.end();
literal_set::iterator it = unfixed_lits.begin(), end = unfixed_lits.end();
for (; it != end; ++it) {
literal lit = *it;
if (value(lit) == l_true) {
to_keep.insert(lit);
}
else {
unfixed_vars.remove(lit.var());
}
}
unfixed = to_keep;
unfixed_lits = to_keep;
}
void solver::extract_fixed_consequences(unsigned& start, literal_set const& assumptions, literal_set& unfixed, vector<literal_vector>& conseq) {
if (scope_lvl() > 1) {
pop(scope_lvl() - 1);
void solver::update_unfixed_literals(literal_set& unfixed_lits, bool_var_set& unfixed_vars) {
literal_vector to_delete;
literal_set::iterator it = unfixed_lits.begin(), end = unfixed_lits.end();
for (; it != end; ++it) {
literal lit = *it;
if (!unfixed_vars.contains(lit.var())) {
to_delete.push_back(lit);
}
}
for (unsigned i = 0; i < to_delete.size(); ++i) {
unfixed_lits.remove(to_delete[i]);
}
}
void solver::extract_fixed_consequences(unsigned& start, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq) {
SASSERT(!inconsistent());
unsigned sz = m_trail.size();
for (unsigned i = start; i < sz; ++i) {
for (unsigned i = start; i < sz && lvl(m_trail[i]) <= 1; ++i) {
extract_fixed_consequences(m_trail[i], assumptions, unfixed, conseq);
}
start = sz;
@ -3288,7 +3388,7 @@ namespace sat {
}
}
void solver::extract_fixed_consequences(literal lit, literal_set const& assumptions, literal_set& unfixed, vector<literal_vector>& conseq) {
void solver::extract_fixed_consequences(literal lit, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq) {
index_set s;
if (assumptions.contains(lit)) {
s.insert(lit.index());
@ -3298,14 +3398,14 @@ namespace sat {
extract_assumptions(lit, s);
}
m_antecedents.insert(lit.var(), s);
if (unfixed.contains(lit)) {
if (unfixed.contains(lit.var())) {
literal_vector cons;
cons.push_back(lit);
index_set::iterator it = s.begin(), end = s.end();
for (; it != end; ++it) {
cons.push_back(to_literal(*it));
}
unfixed.remove(lit);
unfixed.remove(lit.var());
conseq.push_back(cons);
}
}

12
src/sat/sat_solver.h
View file

@ -457,11 +457,17 @@ namespace sat {
lbool get_consequences(literal_vector const& assms, literal_vector const& lits, vector<literal_vector>& conseq);
void delete_unfixed(literal_set& unfixed);
lbool get_bounded_consequences(literal_vector const& assms, bool_var_vector const& vars, vector<literal_vector>& conseq);
void extract_fixed_consequences(unsigned& start, literal_set const& assumptions, literal_set& unfixed, vector<literal_vector>& conseq);
void delete_unfixed(literal_set& unfixed_lits, bool_var_set& unfixed_vars);
void extract_fixed_consequences(literal lit, literal_set const& assumptions, literal_set& unfixed, vector<literal_vector>& conseq);
void extract_fixed_consequences(unsigned& start, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq);
void extract_fixed_consequences(literal lit, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq);
void update_unfixed_literals(literal_set& unfixed_lits, bool_var_set& unfixed_vars);
void fixup_consequence_core();
// -----------------------
//

11
src/sat/sat_solver/inc_sat_solver.cpp
View file

@ -252,12 +252,17 @@ public:
m_solver.pop_to_base_level();
lbool r = internalize_formulas();
if (r != l_true) return r;
r = internalize_vars(vars, bvars);
if (r != l_true) return r;
r = internalize_assumptions(assumptions.size(), assumptions.c_ptr(), dep2asm);
if (r != l_true) return r;
r = internalize_vars(vars, bvars);
r = m_solver.get_consequences(m_asms, bvars, lconseq);
if (r == l_false) return r;
if (r == l_false) {
if (!m_asms.empty()) {
extract_core(dep2asm);
}
return r;
}
// build map from bound variables to
// the consequences that cover them.