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add cube functionality

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-09-24 13:29:46 -07:00
parent ae9a6664d4
commit 82922d92f7
4 changed files with 83 additions and 58 deletions
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124
src/sat/sat_lookahead.cpp
View file

@ -821,6 +821,15 @@ namespace sat {
return out; return out;
} }
void lookahead::display_search_string() {
printf("\r");
std::stringstream strm;
strm << pp_prefix(m_prefix, m_trail_lim.size());
for (unsigned i = 0; i < 50; ++i) strm << " ";
printf(strm.str().c_str());
fflush(stdout);
}
void lookahead::construct_lookahead_table() { void lookahead::construct_lookahead_table() {
literal u = get_child(null_literal), v = null_literal; literal u = get_child(null_literal), v = null_literal;
unsigned offset = 0; unsigned offset = 0;
@ -1710,47 +1719,6 @@ namespace sat {
return true; return true;
} }
void lookahead::cube() {
m_model.reset();
scoped_level _sl(*this, c_fixed_truth);
literal_vector trail;
m_search_mode = lookahead_mode::searching;
double freevars_threshold = 0;
while (true) {
TRACE("sat", display(tout););
inc_istamp();
checkpoint();
literal l = choose();
if (inconsistent()) {
freevars_threshold = m_freevars.size();
if (!backtrack(trail)) return;
continue;
}
unsigned depth = m_trail_lim.size();
if (l == null_literal ||
(m_config.m_cube_cutoff != 0 && depth == m_config.m_cube_cutoff) ||
(m_config.m_cube_cutoff == 0 && m_freevars.size() < freevars_threshold)) {
display_cube(std::cout);
set_conflict();
if (!backtrack(trail)) return;
freevars_threshold *= (1.0 - pow(m_config.m_cube_fraction, depth));
continue;
}
TRACE("sat", tout << "choose: " << l << " " << trail << "\n";);
++m_stats.m_decisions;
IF_VERBOSE(1, printf("\r");
std::stringstream strm;
strm << pp_prefix(m_prefix, m_trail_lim.size());
for (unsigned i = 0; i < 50; ++i) strm << " ";
printf(strm.str().c_str());
fflush(stdout);
);
push(l, c_fixed_truth);
trail.push_back(l);
SASSERT(inconsistent() || !is_unsat());
}
}
lbool lookahead::search() { lbool lookahead::search() {
m_model.reset(); m_model.reset();
scoped_level _sl(*this, c_fixed_truth); scoped_level _sl(*this, c_fixed_truth);
@ -1770,19 +1738,73 @@ namespace sat {
} }
TRACE("sat", tout << "choose: " << l << " " << trail << "\n";); TRACE("sat", tout << "choose: " << l << " " << trail << "\n";);
++m_stats.m_decisions; ++m_stats.m_decisions;
IF_VERBOSE(1, printf("\r"); IF_VERBOSE(1, display_search_string(););
std::stringstream strm;
strm << pp_prefix(m_prefix, m_trail_lim.size());
for (unsigned i = 0; i < 50; ++i) strm << " ";
printf(strm.str().c_str());
fflush(stdout);
);
push(l, c_fixed_truth); push(l, c_fixed_truth);
trail.push_back(l); trail.push_back(l);
SASSERT(inconsistent() || !is_unsat()); SASSERT(inconsistent() || !is_unsat());
} }
} }
bool lookahead::backtrack(literal_vector& trail, svector<bool> & is_decision) {
while (inconsistent()) {
if (trail.empty()) return false;
if (is_decision.back()) {
pop();
trail.back().neg();
assign(trail.back());
is_decision.back() = false;
propagate();
}
else {
trail.pop_back();
is_decision.pop_back();
}
}
return true;
}
lbool lookahead::cube() {
lbool result = l_false;
init_search();
m_model.reset();
scoped_level _sl(*this, c_fixed_truth);
literal_vector cube;
svector<bool> is_decision;
m_search_mode = lookahead_mode::searching;
double freevars_threshold = 0;
while (true) {
TRACE("sat", display(tout););
inc_istamp();
checkpoint();
literal l = choose();
if (inconsistent()) {
TRACE("sat", tout << "inconsistent: " << cube << "\n";);
freevars_threshold = m_freevars.size();
if (!backtrack(cube, is_decision)) return result;
continue;
}
if (l == null_literal) {
return l_true;
}
unsigned depth = cube.size();
if ((m_config.m_cube_cutoff != 0 && depth == m_config.m_cube_cutoff) ||
(m_config.m_cube_cutoff == 0 && m_freevars.size() < freevars_threshold)) {
display_cube(std::cout, cube);
freevars_threshold *= (1.0 - pow(m_config.m_cube_fraction, depth));
result = l_undef;
set_conflict();
if (!backtrack(cube, is_decision)) return result;
continue;
}
TRACE("sat", tout << "choose: " << l << " cube: " << cube << "\n";);
++m_stats.m_decisions;
push(l, c_fixed_truth);
cube.push_back(l);
is_decision.push_back(true);
SASSERT(inconsistent() || !is_unsat());
}
}
void lookahead::init_model() { void lookahead::init_model() {
m_model.reset(); m_model.reset();
for (unsigned i = 0; i < m_num_vars; ++i) { for (unsigned i = 0; i < m_num_vars; ++i) {
@ -1801,12 +1823,12 @@ namespace sat {
} }
} }
std::ostream& lookahead::display_cube(std::ostream& out) const { std::ostream& lookahead::display_cube(std::ostream& out, literal_vector const& cube) const {
out << "c"; out << "c";
for (literal l : m_assumptions) { for (literal l : cube) {
out << " " << ~l; out << " " << ~l;
} }
return out << "\n"; return out << " 0\n";
} }
std::ostream& lookahead::display_binary(std::ostream& out) const { std::ostream& lookahead::display_binary(std::ostream& out) const {

6
src/sat/sat_lookahead.h
View file

@ -444,13 +444,15 @@ namespace sat {
void assign(literal l); void assign(literal l);
void propagated(literal l); void propagated(literal l);
bool backtrack(literal_vector& trail); bool backtrack(literal_vector& trail);
bool backtrack(literal_vector& trail, svector<bool> & is_decision);
lbool search(); lbool search();
void init_model(); void init_model();
std::ostream& display_binary(std::ostream& out) const; std::ostream& display_binary(std::ostream& out) const;
std::ostream& display_clauses(std::ostream& out) const; std::ostream& display_clauses(std::ostream& out) const;
std::ostream& display_values(std::ostream& out) const; std::ostream& display_values(std::ostream& out) const;
std::ostream& display_lookahead(std::ostream& out) const; std::ostream& display_lookahead(std::ostream& out) const;
std::ostream& display_cube(std::ostream& out) const; std::ostream& display_cube(std::ostream& out, literal_vector const& cube) const;
void display_search_string();
void init_search(); void init_search();
void checkpoint(); void checkpoint();
@ -486,7 +488,7 @@ namespace sat {
If cut-depth != 0, then it is used to control the depth of cuts. If cut-depth != 0, then it is used to control the depth of cuts.
Otherwise, cut-fraction gives an adaptive threshold for creating cuts. Otherwise, cut-fraction gives an adaptive threshold for creating cuts.
*/ */
void cube(); lbool cube();
literal select_lookahead(literal_vector const& assumptions, bool_var_vector const& vars); literal select_lookahead(literal_vector const& assumptions, bool_var_vector const& vars);
/** /**

9
src/sat/sat_solver.cpp
View file

@ -857,8 +857,7 @@ namespace sat {
return lookahead_search(); return lookahead_search();
} }
if (m_config.m_lookahead_cube && num_lits == 0) { if (m_config.m_lookahead_cube && num_lits == 0) {
lookahead_cube(); return lookahead_cube();
return l_undef;
} }
if (m_config.m_local_search) { if (m_config.m_local_search) {
return do_local_search(num_lits, lits); return do_local_search(num_lits, lits);
@ -952,16 +951,18 @@ namespace sat {
return r; return r;
} }
void solver::lookahead_cube() { lbool solver::lookahead_cube() {
lookahead lh(*this); lookahead lh(*this);
lbool r = l_undef;
try { try {
lh.cube(); r = lh.cube();
} }
catch (z3_exception&) { catch (z3_exception&) {
lh.collect_statistics(m_aux_stats); lh.collect_statistics(m_aux_stats);
throw; throw;
} }
lh.collect_statistics(m_aux_stats); lh.collect_statistics(m_aux_stats);
return r;
} }
lbool solver::lookahead_search() { lbool solver::lookahead_search() {

2
src/sat/sat_solver.h
View file

@ -403,7 +403,7 @@ namespace sat {
void exchange_par(); void exchange_par();
lbool check_par(unsigned num_lits, literal const* lits); lbool check_par(unsigned num_lits, literal const* lits);
lbool lookahead_search(); lbool lookahead_search();
void lookahead_cube(); lbool lookahead_cube();
lbool do_local_search(unsigned num_lits, literal const* lits); lbool do_local_search(unsigned num_lits, literal const* lits);
lbool do_ccc(); lbool do_ccc();