mirror of
https://github.com/Z3Prover/z3
synced 2025-04-13 20:38:43 +00:00
Lookahead clause size optimization. Fixed some missing propagations
This commit is contained in:
Miguel Neves
parent
4394ce96ae
commit
806690571e
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@ -155,7 +155,7 @@ namespace sat {
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if (is_stamped(~w)) {
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// u \/ v, ~v \/ w, u \/ ~w => u is unit
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TRACE("sat", tout << "tc1: " << u << "\n";);
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assign(u);
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propagated(u);
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return false;
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}
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if (m_num_tc1 < m_config.m_tc1_limit) {
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@ -181,14 +181,14 @@ namespace sat {
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set_bstamps(~u);
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if (is_stamped(~v)) {
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TRACE("sat", tout << "try_add_binary: " << u << "\n";);
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assign(u); // u \/ ~v, u \/ v => u is a unit literal
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propagated(u); // u \/ ~v, u \/ v => u is a unit literal
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}
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else if (!is_stamped(v) && add_tc1(u, v)) {
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// u \/ v is not in index
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set_bstamps(~v);
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if (is_stamped(~u)) {
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TRACE("sat", tout << "try_add_binary: " << v << "\n";);
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assign(v); // v \/ ~u, u \/ v => v is a unit literal
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TRACE("sat", tout << "try_add_binary: " << v << "\n";);
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propagated(v); // v \/ ~u, u \/ v => v is a unit literal
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}
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else if (add_tc1(v, u)) {
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update_prefix(u);
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@ -407,6 +407,37 @@ namespace sat {
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return true;
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}
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bool lookahead::missed_propagation() const {
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for (literal l1 : m_trail) {
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SASSERT(is_true(l1));
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for (literal l2 : m_binary[l1.index()]) {
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if (is_undef(l2)) return true;
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}
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unsigned sz = m_ternary_count[(~l1).index()];
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for (binary b : m_ternary[(~l1).index()]) {
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if (sz-- == 0) break;
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if ((is_false(b.m_u) && is_undef(b.m_v)) || (is_false(b.m_v) && is_undef(b.m_u)))
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return true;
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}
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}
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for (nary * n : m_nary_clauses) {
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if (n->size() == 1 && !is_true(n->get_head())) {
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for (literal lit : *n) {
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if (is_undef(lit)) return true;
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}
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}
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}
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return false;
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}
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bool lookahead::missed_conflict() const {
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if (inconsistent()) return false;
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for (nary * n : m_nary_clauses) {
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if (n->size() == 0) return true;
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}
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return false;
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}
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void lookahead::init_pre_selection(unsigned level) {
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switch (m_config.m_reward_type) {
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case ternary_reward: {
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@ -1098,11 +1129,19 @@ namespace sat {
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}
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void lookahead::lookahead_backtrack() {
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while (!m_trail.empty() && is_undef(m_trail.back())) {
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literal lit = null_literal;
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while (!m_trail.empty() && is_undef((lit = m_trail.back()))) {
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if (m_qhead == m_trail.size()) {
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unsigned sz = m_nary_count[(~lit).index()];
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for (nary* n : m_nary[(~lit).index()]) {
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if (sz-- == 0) break;
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n->inc_size();
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}
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--m_qhead;
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}
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m_trail.pop_back();
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}
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SASSERT(m_trail_lim.empty() || m_trail.size() >= m_trail_lim.back());
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m_qhead = std::min(m_qhead, m_trail.size());
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}
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//
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@ -1137,14 +1176,15 @@ namespace sat {
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lbool lookahead::propagate_ternary(literal l1, literal l2) {
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if (is_fixed(l1)) {
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if (is_false(l1)) {
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if (is_undef(l2)) {
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propagated(l2);
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}
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else if (is_false(l2)) {
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if (is_false(l2)) {
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TRACE("sat", tout << l1 << " " << l2 << " " << "\n";);
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set_conflict();
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return l_false;
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}
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return l_false;
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else if (is_undef(l2)) {
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propagated(l2);
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}
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return l_true;
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}
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else {
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return l_true;
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@ -1298,10 +1338,11 @@ namespace sat {
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unsigned sz = m_nary_count[(~l).index()];
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literal lit;
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SASSERT(m_search_mode == lookahead_mode::searching);
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for (nary * n : m_nary[(~l).index()]) {
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for (nary* n : m_nary[(~l).index()]) {
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if (sz-- == 0) break;
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unsigned len = n->dec_size();
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if (m_inconsistent) continue;
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if (is_true(n->get_head())) continue;
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if (inconsistent()) continue;
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if (len <= 1) continue; // already processed
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// find the two unassigned literals, if any
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if (len == 2) {
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@ -1357,53 +1398,35 @@ namespace sat {
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void lookahead::propagate_clauses_lookahead(literal l) {
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// clauses where l is negative
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unsigned sz = m_nary_count[(~l).index()];
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literal lit;
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SASSERT(m_search_mode == lookahead_mode::lookahead1 ||
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m_search_mode == lookahead_mode::lookahead2);
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for (nary* n : m_nary[(~l).index()]) {
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if (sz-- == 0) break;
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if (is_true(n->get_head())) {
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continue;
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}
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literal l1 = null_literal;
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literal l2 = null_literal;
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bool skip_clause = false;
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unsigned nonfixed = 0;
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for (literal lit : *n) {
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if (!is_fixed(lit)) {
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++nonfixed;
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if (l1 == null_literal) {
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l1 = lit;
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}
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else if (l2 == null_literal) {
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l2 = lit;
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unsigned nonfixed = n->dec_size();
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if (is_true(n->get_head())) continue;
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if (inconsistent()) continue;
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if (nonfixed <= 1) {
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bool found_conflict = true;
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for (literal lit : *n) {
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if (!is_fixed(lit)) {
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propagated(lit);
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found_conflict = false;
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break;
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}
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else if (m_search_mode == lookahead_mode::lookahead2) {
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skip_clause = true;
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else if (is_true(lit)) {
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n->set_head(lit);
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found_conflict = false;
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break;
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}
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}
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else if (is_true(lit)) {
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n->set_head(lit);
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skip_clause = true;
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break;
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if (found_conflict) {
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set_conflict();
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continue;
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}
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}
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if (skip_clause) {
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// skip, the clause
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}
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else if (l1 == null_literal) {
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set_conflict();
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return;
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}
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else if (l2 == null_literal) {
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propagated(l1);
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}
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else {
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else if (m_search_mode == lookahead_mode::lookahead1) {
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SASSERT(nonfixed >= 2);
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SASSERT(m_search_mode == lookahead_mode::lookahead1);
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switch (m_config.m_reward_type) {
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case heule_schur_reward: {
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double to_add = 0;
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@ -1418,9 +1441,35 @@ namespace sat {
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case heule_unit_reward:
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m_lookahead_reward += pow(0.5, nonfixed);
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break;
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case march_cu_reward:
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m_lookahead_reward += 3.3 * pow(0.5, nonfixed - 2);
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break;
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case ternary_reward:
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if (nonfixed == 2) {
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m_lookahead_reward += (*m_heur)[l1.index()] * (*m_heur)[l2.index()];
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literal l1 = null_literal;
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literal l2 = null_literal;
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for (literal lit : *n) {
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if (!is_fixed(lit)) {
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if (l1 == null_literal) {
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l1 = lit;
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}
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else {
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SASSERT(l2 != null_literal);
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l2 = lit;
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break;
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}
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}
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}
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if (l1 == null_literal) {
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set_conflict();
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continue;
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}
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else if (l2 == null_literal) {
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propagated(l1);
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}
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else {
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m_lookahead_reward += (*m_heur)[l1.index()] * (*m_heur)[l2.index()];
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}
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}
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else {
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m_lookahead_reward += (double)0.001;
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@ -1431,6 +1480,14 @@ namespace sat {
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}
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}
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}
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// clauses where l is positive:
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sz = m_nary_count[l.index()];
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for (nary* n : m_nary[l.index()]) {
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if (sz-- == 0) break;
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if (m_stamp[l.var()] > m_stamp[n->get_head().var()]) {
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n->set_head(l);
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}
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}
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}
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void lookahead::remove_clause_at(literal l, nary& n) {
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@ -1567,9 +1624,9 @@ namespace sat {
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void lookahead::propagate_binary(literal l) {
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literal_vector const& lits = m_binary[l.index()];
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TRACE("sat", tout << l << " => " << lits << "\n";);
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for (literal l : lits) {
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for (literal lit : lits) {
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if (inconsistent()) break;
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assign(l);
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assign(lit);
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}
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}
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@ -1584,6 +1641,8 @@ namespace sat {
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propagate_clauses(m_trail[m_qhead++]);
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}
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SASSERT(m_qhead == m_trail.size() || (inconsistent() && m_qhead < m_trail.size()));
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//SASSERT(!missed_conflict());
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//SASSERT(inconsistent() || !missed_propagation());
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TRACE("sat_verbose", display(tout << scope_lvl() << " " << (inconsistent()?"unsat":"sat") << "\n"););
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}
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@ -1600,6 +1659,7 @@ namespace sat {
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checkpoint();
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literal lit = m_lookahead[i].m_lit;
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if (lit == last_changed) {
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SASSERT(!change);
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break;
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}
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if (scope_lvl() == 1) {
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@ -1812,6 +1872,7 @@ namespace sat {
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lookahead_backtrack();
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assign(l);
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propagate();
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//SASSERT(!inconsistent());
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unsigned old_sz = m_trail.size();
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bool change = true;
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literal last_changed = null_literal;
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@ -1847,6 +1908,7 @@ namespace sat {
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propagate();
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change = true;
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last_changed = lit;
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m_wstack.push_back(~lit);
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}
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}
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base += 2 * m_lookahead.size();
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@ -90,7 +90,7 @@ namespace sat {
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m_min_cutoff = 30;
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m_preselect = false;
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m_level_cand = 600;
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m_delta_rho = (double)0.25;
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m_delta_rho = (double)0.85;
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m_dl_max_iterations = 2;
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m_tc1_limit = 10000000;
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m_reward_type = ternary_reward;
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@ -340,6 +340,8 @@ namespace sat {
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std::ostream& display_candidates(std::ostream& out) const;
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bool is_unsat() const;
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bool is_sat() const;
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bool missed_propagation() const;
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bool missed_conflict() const;
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void init_pre_selection(unsigned level);
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void ensure_H(unsigned level);
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void h_scores(svector<double>& h, svector<double>& hp);
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@ -503,7 +505,7 @@ namespace sat {
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unsigned do_double(literal l, unsigned& base);
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unsigned double_look(literal l, unsigned& base);
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void set_conflict() { TRACE("sat", tout << "conflict\n";); m_inconsistent = true; }
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bool inconsistent() { return m_inconsistent; }
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bool inconsistent() const { return m_inconsistent; }
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unsigned scope_lvl() const { return m_trail_lim.size(); }
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