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fix transitive reduction bug, eliminate blocked tag on binary clauses, separate BIG structure from scc

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-12-13 02:38:06 -08:00
commit 71c52396cb
26 changed files with 572 additions and 355 deletions
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95
src/sat/sat_scc.cpp
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@ -234,102 +234,10 @@ namespace sat {
return to_elim.size();
}
void scc::init_big(bool learned) {
unsigned num_lits = m_solver.num_vars() * 2;
m_dag.reset();
m_roots.reset();
m_dag.resize(num_lits, 0);
m_roots.resize(num_lits, true);
SASSERT(num_lits == m_dag.size() && num_lits == m_roots.size());
for (unsigned l_idx = 0; l_idx < num_lits; l_idx++) {
literal u = to_literal(l_idx);
if (m_solver.was_eliminated(u.var()))
continue;
auto& edges = m_dag[l_idx];
for (watched const& w : m_solver.m_watches[l_idx]) {
if (learned ? w.is_binary_clause() : w.is_binary_unblocked_clause()) {
literal v = w.get_literal();
m_roots[v.index()] = false;
edges.push_back(v);
}
}
shuffle<literal>(edges.size(), edges.c_ptr(), m_rand);
}
init_dfs_num(learned);
}
struct scc::pframe {
literal m_parent;
literal m_child;
pframe(literal p, literal c):
m_parent(p), m_child(c) {}
literal child() const { return m_child; }
literal parent() const { return m_parent; }
};
void scc::init_dfs_num(bool learned) {
unsigned num_lits = m_solver.num_vars() * 2;
m_left.reset();
m_right.reset();
m_root.reset();
m_parent.reset();
m_left.resize(num_lits, 0);
m_right.resize(num_lits, -1);
m_root.resize(num_lits, null_literal);
m_parent.resize(num_lits, null_literal);
for (unsigned i = 0; i < num_lits; ++i) {
m_root[i] = to_literal(i);
m_parent[i] = to_literal(i);
}
svector<pframe> todo;
// retrieve literals that have no predecessors
for (unsigned l_idx = 0; l_idx < num_lits; l_idx++) {
literal u(to_literal(l_idx));
if (m_roots[u.index()]) {
todo.push_back(pframe(null_literal, u));
}
}
shuffle<pframe>(todo.size(), todo.c_ptr(), m_rand);
int dfs_num = 0;
while (!todo.empty()) {
literal u = todo.back().child();
if (m_left[u.index()] > 0) {
// already visited
if (m_right[u.index()] < 0) {
m_right[u.index()] = ++dfs_num;
}
todo.pop_back();
}
else {
SASSERT(m_left[u.index()] == 0);
m_left[u.index()] = ++dfs_num;
literal p = todo.back().parent();
if (p != null_literal) {
m_root[u.index()] = m_root[p.index()];
m_parent[u.index()] = p;
}
for (literal v : m_dag[u.index()]) {
if (m_left[v.index()] == 0) {
todo.push_back(pframe(u, v));
}
}
}
}
for (unsigned i = 0; i < num_lits; ++i) {
if (m_right[i] < 0) {
VERIFY(m_left[i] == 0);
m_left[i] = ++dfs_num;
m_right[i] = ++dfs_num;
}
}
for (unsigned i = 0; i < num_lits; ++i) {
VERIFY(m_left[i] < m_right[i]);
}
}
unsigned scc::reduce_tr(bool learned) {
unsigned num_lits = m_solver.num_vars() * 2;
init_big(learned);
unsigned idx = 0;
unsigned elim = m_num_elim_bin;
for (watch_list & wlist : m_solver.m_watches) {
@ -343,6 +251,7 @@ namespace sat {
literal v = w.get_literal();
if (reaches(u, v) && u != get_parent(v)) {
++m_num_elim_bin;
m_solver.get_wlist(~v).erase(watched(~u, w.is_learned()));
}
else {
*itprev = *it;