mirror of
https://github.com/Z3Prover/z3
synced 2025-10-11 02:08:07 +00:00
add lrb/chb and experiment with them
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
commit
e0a86ccc1a
28 changed files with 459 additions and 281 deletions
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@ -174,6 +174,11 @@ namespace sat {
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m_phase.push_back(PHASE_NOT_AVAILABLE);
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m_prev_phase.push_back(PHASE_NOT_AVAILABLE);
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m_assigned_since_gc.push_back(false);
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m_last_conflict.push_back(0);
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m_last_propagation.push_back(0);
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m_participated.push_back(0);
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m_canceled.push_back(0);
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m_reasoned.push_back(0);
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m_case_split_queue.mk_var_eh(v);
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m_simplifier.insert_elim_todo(v);
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SASSERT(!was_eliminated(v));
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@ -580,6 +585,29 @@ namespace sat {
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if (m_ext && m_external[v])
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m_ext->asserted(l);
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switch (m_config.m_branching_heuristic) {
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case BH_VSIDS:
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break;
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case BH_CHB:
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m_last_propagation[v] = m_stats.m_conflict;
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break;
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case BH_LRB:
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m_participated[v] = 0;
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m_reasoned[v] = 0;
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break;
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}
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if (m_config.m_anti_exploration) {
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uint64 age = m_stats.m_conflict - m_canceled[v];
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if (age > 0) {
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double decay = pow(0.95, age);
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m_activity[v] = static_cast<unsigned>(m_activity[v] * decay);
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// NB. MapleSAT does not update canceled.
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m_canceled[v] = m_stats.m_conflict;
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m_case_split_queue.activity_changed_eh(v, false);
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}
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}
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SASSERT(!l.sign() || m_phase[v] == NEG_PHASE);
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SASSERT(l.sign() || m_phase[v] == POS_PHASE);
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@ -771,7 +799,11 @@ namespace sat {
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}
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bool solver::propagate(bool update) {
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unsigned qhead = m_qhead;
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bool r = propagate_core(update);
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if (m_config.m_branching_heuristic == BH_CHB) {
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update_chb_activity(r, qhead);
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}
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CASSERT("sat_propagate", check_invariant());
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CASSERT("sat_missed_prop", check_missed_propagation());
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return r;
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@ -1064,6 +1096,18 @@ namespace sat {
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}
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while (!m_case_split_queue.empty()) {
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if (m_config.m_anti_exploration) {
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next = m_case_split_queue.min_var();
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auto age = m_stats.m_conflict - m_canceled[next];
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while (age > 0) {
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double decay = pow(0.95, age);
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m_activity[next] = static_cast<unsigned>(m_activity[next] * pow(0.95, age));
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m_case_split_queue.activity_changed_eh(next, false);
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m_canceled[next] = m_stats.m_conflict;
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next = m_case_split_queue.min_var();
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age = m_stats.m_conflict - m_canceled[next];
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}
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}
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next = m_case_split_queue.next_var();
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if (value(next) == l_undef && !was_eliminated(next))
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return next;
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@ -1828,6 +1872,9 @@ namespace sat {
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m_conflicts_since_restart++;
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m_conflicts_since_gc++;
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m_stats.m_conflict++;
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if (m_step_size > m_config.m_step_size_min) {
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m_step_size -= m_config.m_step_size_dec;
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}
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m_conflict_lvl = get_max_lvl(m_not_l, m_conflict);
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TRACE("sat", tout << "conflict detected at level " << m_conflict_lvl << " for ";
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@ -2175,7 +2222,16 @@ namespace sat {
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SASSERT(var < num_vars());
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if (!is_marked(var) && var_lvl > 0) {
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mark(var);
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inc_activity(var);
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switch (m_config.m_branching_heuristic) {
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case BH_VSIDS:
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inc_activity(var);
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break;
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case BH_CHB:
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m_last_conflict[var] = m_stats.m_conflict;
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break;
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default:
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break;
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}
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if (var_lvl == m_conflict_lvl)
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num_marks++;
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else
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@ -2431,6 +2487,9 @@ namespace sat {
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\brief Reset the mark of the variables in the current lemma.
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*/
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void solver::reset_lemma_var_marks() {
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if (m_config.m_branching_heuristic == BH_LRB) {
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update_lrb_reasoned();
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}
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literal_vector::iterator it = m_lemma.begin();
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literal_vector::iterator end = m_lemma.end();
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SASSERT(!is_marked((*it).var()));
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@ -2441,6 +2500,58 @@ namespace sat {
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}
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}
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void solver::update_lrb_reasoned() {
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unsigned sz = m_lemma.size();
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SASSERT(!is_marked(m_lemma[0].var()));
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mark(m_lemma[0].var());
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for (unsigned i = m_lemma.size(); i > 0; ) {
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--i;
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justification js = m_justification[m_lemma[i].var()];
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switch (js.get_kind()) {
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case justification::NONE:
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break;
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case justification::BINARY:
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update_lrb_reasoned(js.get_literal());
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break;
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case justification::TERNARY:
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update_lrb_reasoned(js.get_literal1());
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update_lrb_reasoned(js.get_literal2());
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break;
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case justification::CLAUSE: {
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clause & c = *(m_cls_allocator.get_clause(js.get_clause_offset()));
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for (unsigned i = 0; i < c.size(); ++i) {
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update_lrb_reasoned(c[i]);
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}
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break;
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}
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case justification::EXT_JUSTIFICATION: {
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fill_ext_antecedents(m_lemma[i], js);
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literal_vector::iterator it = m_ext_antecedents.begin();
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literal_vector::iterator end = m_ext_antecedents.end();
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for (; it != end; ++it) {
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update_lrb_reasoned(*it);
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}
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break;
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}
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}
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}
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reset_mark(m_lemma[0].var());
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for (unsigned i = m_lemma.size(); i > sz; ) {
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--i;
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reset_mark(m_lemma[i].var());
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}
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m_lemma.shrink(sz);
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}
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void solver::update_lrb_reasoned(literal lit) {
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bool_var v = lit.var();
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if (!is_marked(v)) {
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mark(v);
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m_reasoned[v]++;
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m_lemma.push_back(lit);
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}
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}
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/**
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\brief Apply dynamic subsumption resolution to new lemma.
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Only binary and ternary clauses are used.
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@ -2617,6 +2728,18 @@ namespace sat {
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bool_var v = l.var();
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SASSERT(value(v) == l_undef);
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m_case_split_queue.unassign_var_eh(v);
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if (m_config.m_branching_heuristic == BH_LRB) {
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uint64 interval = m_stats.m_conflict - m_last_propagation[v];
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if (interval > 0) {
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auto activity = m_activity[v];
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auto reward = (m_config.m_reward_offset * (m_participated[v] + m_reasoned[v])) / interval;
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m_activity[v] = static_cast<unsigned>(m_step_size * reward + ((1 - m_step_size) * activity));
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m_case_split_queue.activity_changed_eh(v, m_activity[v] > activity);
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}
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}
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if (m_config.m_anti_exploration) {
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m_canceled[v] = m_stats.m_conflict;
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}
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}
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m_trail.shrink(old_sz);
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m_qhead = old_sz;
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@ -2799,6 +2922,8 @@ namespace sat {
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m_probing.updt_params(p);
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m_scc.updt_params(p);
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m_rand.set_seed(m_config.m_random_seed);
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m_step_size = m_config.m_step_size_init;
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}
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void solver::collect_param_descrs(param_descrs & d) {
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@ -2836,6 +2961,7 @@ namespace sat {
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// -----------------------
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void solver::rescale_activity() {
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SASSERT(m_config.m_branching_heuristic == BH_VSIDS);
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svector<unsigned>::iterator it = m_activity.begin();
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svector<unsigned>::iterator end = m_activity.end();
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for (; it != end; ++it) {
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@ -2844,6 +2970,18 @@ namespace sat {
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m_activity_inc >>= 14;
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}
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void solver::update_chb_activity(bool is_sat, unsigned qhead) {
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SASSERT(m_config.m_branching_heuristic == BH_CHB);
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double multiplier = m_config.m_reward_offset * (is_sat ? m_config.m_reward_multiplier : 1.0);
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for (unsigned i = qhead; i < m_trail.size(); ++i) {
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auto v = m_trail[i].var();
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auto reward = multiplier / (m_stats.m_conflict - m_last_conflict[v] + 1);
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auto activity = m_activity[v];
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m_activity[v] = static_cast<unsigned>(m_step_size * reward + ((1.0 - m_step_size) * activity));
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m_case_split_queue.activity_changed_eh(v, m_activity[v] > activity);
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}
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}
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// -----------------------
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//
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// Iterators
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