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add options to perform transitive reduction and add hyper binary clauses

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-11-27 10:53:22 -08:00
parent 15d8532d27
commit 62e3906957
9 changed files with 189 additions and 25 deletions
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64
src/sat/sat_lookahead.cpp
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@ -17,9 +17,10 @@ Author:
Notes:
--*/
#include "sat_solver.h"
#include "sat_extension.h"
#include "sat_lookahead.h"
#include "sat/sat_solver.h"
#include "sat/sat_extension.h"
#include "sat/sat_lookahead.h"
#include "util/union_find.h"
namespace sat {
lookahead::scoped_ext::scoped_ext(lookahead& p): p(p) {
@ -648,7 +649,6 @@ namespace sat {
TRACE("sat", display_scc(tout););
}
void lookahead::init_scc() {
std::cerr << "init-scc\n";
inc_bstamp();
for (unsigned i = 0; i < m_candidates.size(); ++i) {
literal lit(m_candidates[i].m_var, false);
@ -2290,20 +2290,51 @@ namespace sat {
elim_eqs elim(m_s);
elim(roots, to_elim);
#if 0
// TBD:
// Finally create a new graph between parents
// based on the arcs in the the m_dfs[index].m_next structure
// Visit all nodes, assign DFS numbers
// Then prune binary clauses that differ in DFS number more than 1
// Add binary clauses that have DFS number 1, but no companion binary clause.
//
#endif
if (get_config().m_lookahead_simplify_bca) {
add_hyper_binary();
}
}
}
m_lookahead.reset();
m_lookahead.reset();
}
/**
\brief reduction based on binary implication graph
*/
void lookahead::add_hyper_binary() {
unsigned num_lits = m_s.num_vars() * 2;
union_find_default_ctx ufctx;
union_find<union_find_default_ctx> uf(ufctx);
for (unsigned i = 0; i < num_lits; ++i) uf.mk_var();
for (unsigned idx = 0; idx < num_lits; ++idx) {
literal u = get_parent(to_literal(idx));
if (null_literal != u) {
for (watched const& w : m_s.m_watches[idx]) {
if (!w.is_binary_clause()) continue;
literal v = get_parent(w.get_literal());
if (null_literal != v) {
uf.merge(u.index(), v.index());
}
}
}
}
unsigned disconnected = 0;
for (unsigned i = 0; i < m_binary.size(); ++i) {
literal u = to_literal(i);
if (u == get_parent(u)) {
for (literal v : m_binary[i]) {
if (v == get_parent(v) && uf.find(u.index()) != uf.find(v.index())) {
++disconnected;
uf.merge(u.index(), v.index());
m_s.mk_clause(~u, v, true);
}
}
}
}
IF_VERBOSE(10, verbose_stream() << "(sat-lookahead :bca " << disconnected << ")\n";);
m_stats.m_bca += disconnected;
}
void lookahead::normalize_parents() {
@ -2378,6 +2409,7 @@ namespace sat {
void lookahead::collect_statistics(statistics& st) const {
st.update("lh bool var", m_vprefix.size());
// TBD: keep count of ternary and >3-ary clauses.
st.update("lh bca", m_stats.m_bca);
st.update("lh add binary", m_stats.m_add_binary);
st.update("lh del binary", m_stats.m_del_binary);
st.update("lh propagations", m_stats.m_propagations);