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use failed literal to asym branching

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-11-08 09:14:21 -08:00
parent b099449ce1
commit 0a9946578b
3 changed files with 25 additions and 33 deletions
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51
src/sat/sat_asymm_branch.cpp
View file

@ -62,14 +62,16 @@ namespace sat {
s.propagate(false); // must propagate, since it uses s.push()
if (s.m_inconsistent)
return;
if (!force && m_counter > 0)
if (!force && m_counter > 0) {
m_counter /= 100;
return;
}
CASSERT("asymm_branch", s.check_invariant());
TRACE("asymm_branch_detail", s.display(tout););
report rpt(*this);
svector<char> saved_phase(s.m_phase);
m_counter = 0; // counter is moving down to capture propagate cost.
int limit = -static_cast<int>(m_asymm_branch_limit);
m_counter = 0;
int64 limit = -m_asymm_branch_limit;
std::stable_sort(s.m_clauses.begin(), s.m_clauses.end(), clause_size_lt());
m_counter -= s.m_clauses.size();
SASSERT(s.m_qhead == s.m_trail.size());
@ -111,19 +113,18 @@ namespace sat {
m_counter = -m_counter;
s.m_phase = saved_phase;
m_asymm_branch_limit *= 2;
if (m_asymm_branch_limit > INT_MAX)
m_asymm_branch_limit = INT_MAX;
if (m_asymm_branch_limit > UINT_MAX)
m_asymm_branch_limit = UINT_MAX;
CASSERT("asymm_branch", s.check_invariant());
}
/**
\brief try asymmetric branching on all literals in clause.
*/
bool asymm_branch::process_all(clause & c) {
// try asymmetric branching on all literals in clause.
// clause must not be used for propagation
scoped_detach scoped_d(s, c);
scoped_detach scoped_d(s, c); // clause must not be used for propagation
unsigned sz = c.size();
SASSERT(sz > 0);
unsigned i = 0, new_sz = sz;
@ -180,6 +181,7 @@ namespace sat {
}
new_sz = j;
m_elim_literals += c.size() - new_sz;
// std::cout << "cleanup: " << c.id() << ": " << literal_vector(new_sz, c.begin()) << " delta: " << (c.size() - new_sz) << " " << skip_idx << " " << new_sz << "\n";
switch(new_sz) {
case 0:
s.set_conflict(justification());
@ -235,39 +237,30 @@ namespace sat {
// try asymmetric branching
// clause must not be used for propagation
scoped_detach scoped_d(s, c);
s.push();
bool found_conflict = false;
for (i = 0; i < sz - 1 && !found_conflict; i++) {
found_conflict = propagate_literal(c, ~c[i]);
}
s.pop(1);
unsigned new_sz = c.size();
unsigned flip_position = 2 + m_rand(c.size() - 2); // don't flip on the watch literals.
bool found_conflict = flip_literal_at(c, flip_position, new_sz);
SASSERT(!s.inconsistent());
SASSERT(s.scope_lvl() == 0);
SASSERT(trail_sz == s.m_trail.size());
SASSERT(s.m_qhead == s.m_trail.size());
SASSERT(found_conflict == (i != sz - 1));
if (!found_conflict) {
// clause size can't be reduced.
return true;
}
// clause can be reduced
unsigned new_sz = i+1;
SASSERT(new_sz >= 1);
SASSERT(new_sz < sz);
TRACE("asymm_branch", tout << c << "\nnew_size: " << new_sz << "\n";
for (unsigned i = 0; i < c.size(); i++) tout << static_cast<int>(s.value(c[i])) << " "; tout << "\n";);
// cleanup and attach reduced clause
return cleanup(scoped_d, c, sz, new_sz);
else {
// clause can be reduced
return cleanup(scoped_d, c, flip_position, new_sz);
}
}
void asymm_branch::updt_params(params_ref const & _p) {
sat_asymm_branch_params p(_p);
m_asymm_branch = p.asymm_branch();
m_asymm_branch_rounds = p.asymm_branch_rounds();
m_asymm_branch_limit = p.asymm_branch_limit();
m_asymm_branch_all = p.asymm_branch_all();
if (m_asymm_branch_limit > INT_MAX)
m_asymm_branch_limit = INT_MAX;
if (m_asymm_branch_limit > UINT_MAX)
m_asymm_branch_limit = UINT_MAX;
}
void asymm_branch::collect_param_descrs(param_descrs & d) {

6
src/sat/sat_asymm_branch.h
View file

@ -31,13 +31,13 @@ namespace sat {
struct report;
solver & s;
int m_counter;
int64 m_counter;
random_gen m_rand;
// config
bool m_asymm_branch;
bool m_asymm_branch_all;
unsigned m_asymm_branch_rounds;
unsigned m_asymm_branch_limit;
int64 m_asymm_branch_limit;
// stats
unsigned m_elim_literals;

1
src/sat/sat_asymm_branch_params.pyg
View file

@ -2,6 +2,5 @@ def_module_params(module_name='sat',
class_name='sat_asymm_branch_params',
export=True,
params=(('asymm_branch', BOOL, True, 'asymmetric branching'),
('asymm_branch.rounds', UINT, 32, 'maximum number of rounds of asymmetric branching'),
('asymm_branch.limit', UINT, 100000000, 'approx. maximum number of literals visited during asymmetric branching'),
('asymm_branch.all', BOOL, False, 'asymmetric branching on all literals per clause')))