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https://github.com/Z3Prover/z3
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finish sls code
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
311183e19a
commit
1412c183d4
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@ -18,6 +18,7 @@ Notes:
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--*/
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#include "sat_sls.h"
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#include "sat_solver.h"
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namespace sat {
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@ -50,47 +51,170 @@ namespace sat {
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}
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sls::sls(solver& s): s(s) {
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m_max_tries = 10000;
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m_prob_choose_min_var = 43;
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}
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sls::~sls() {
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}
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#if 0
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bool_var sls::pick_flip() {
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unsigned clause_idx = m_false.choose(m_rand);
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clause const& c = m_clauses[clause_idx];
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unsigned result = UINT_MAX;
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m_min_vars.reset();
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for (unsigned i = 0; i < c.size(); ++i) {
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for (unsigned i = 0; i < m_bin_clauses.size(); ++i) {
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m_alloc.del_clause(m_bin_clauses[i]);
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}
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}
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void sls::flip(bool_var v) {
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}
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bool sls::local_search() {
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for (unsigned i = 0; !m_false.empty() && i < m_max_flips; ++i) {
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flip(pick_flip());
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}
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return m_false.empty();
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}
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#endif
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lbool sls::operator()() {
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#if 0
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lbool sls::operator()(unsigned sz, literal const* tabu) {
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init(sz, tabu);
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for (unsigned i = 0; i < m_max_tries; ++i) {
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if (local_search()) {
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flip();
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if (m_false.empty()) {
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SASSERT(s.check_model(m_model));
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return l_true;
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}
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}
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#endif
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return l_undef;
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}
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void sls::init(unsigned sz, literal const* tabu) {
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init_clauses();
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init_model(sz, tabu);
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init_use();
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}
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void sls::init_clauses() {
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for (unsigned i = 0; i < m_bin_clauses.size(); ++i) {
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m_alloc.del_clause(m_bin_clauses[i]);
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}
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m_clauses.reset();
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clause * const * it = s.begin_clauses();
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clause * const * end = s.end_clauses();
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for (; it != end; ++it) {
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m_clauses.push_back(*it);
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}
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svector<solver::bin_clause> bincs;
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s.collect_bin_clauses(bincs, false);
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literal lits[2];
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for (unsigned i = 0; i < bincs.size(); ++i) {
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lits[0] = bincs[i].first;
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lits[1] = bincs[i].second;
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m_clauses.push_back(m_alloc.mk_clause(2, lits, false));
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}
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}
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void sls::init_model(unsigned sz, literal const* tabu) {
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m_num_true.reset();
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m_model.reset();
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m_model.append(s.get_model());
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m_tabu.reset();
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m_tabu.resize(s.num_vars(), false);
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for (unsigned i = 0; i < sz; ++i) {
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m_model[tabu[i].var()] = tabu[i].sign()?l_false:l_true;
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}
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sz = m_clauses.size();
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for (unsigned i = 0; i < sz; ++i) {
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clause const& c = *m_clauses[i];
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unsigned n = 0;
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unsigned csz = c.size();
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for (unsigned j = 0; j < csz; ++j) {
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if (value_at(c[j], m_model) == l_true) {
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++n;
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}
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}
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m_num_true.push_back(n);
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if (n == 0) {
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m_false.insert(i);
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}
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}
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}
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void sls::init_use() {
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m_use_list.reset();
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m_use_list.resize(s.num_vars()*2);
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unsigned sz = m_clauses.size();
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for (unsigned i = 0; i < sz; ++i) {
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clause const& c = *m_clauses[i];
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unsigned csz = c.size();
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for (unsigned j = 0; j < csz; ++j) {
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m_use_list[c[j].index()].push_back(i);
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}
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}
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}
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unsigned_vector const& sls::get_use(literal lit) {
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SASSERT(lit.index() < m_use_list.size());
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return m_use_list[lit.index()];
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}
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unsigned sls::get_break_count(literal lit, unsigned min_break) {
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SASSERT(value_at(lit, m_model) == l_false);
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unsigned result = 0;
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unsigned_vector const& uses = get_use(~lit);
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unsigned sz = uses.size();
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for (unsigned i = 0; i < sz; ++i) {
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if (m_num_true[uses[i]] == 1) {
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++result;
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if (result > min_break) return result;
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}
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}
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return result;
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}
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bool sls::pick_flip(literal& lit) {
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unsigned clause_idx = m_false.choose(m_rand);
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clause const& c = *m_clauses[clause_idx];
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SASSERT(!c.satisfied_by(m_model));
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unsigned min_break = UINT_MAX;
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unsigned sz = c.size();
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m_min_vars.reset();
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for (unsigned i = 0; i < sz; ++i) {
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lit = c[i];
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if (m_tabu[lit.var()]) continue;
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unsigned break_count = get_break_count(lit, min_break);
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if (break_count < min_break) {
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min_break = break_count;
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m_min_vars.reset();
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m_min_vars.push_back(lit);
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}
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else if (break_count == min_break) {
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m_min_vars.push_back(lit);
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}
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}
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if (min_break == 0 || (m_min_vars.empty() && m_rand(100) >= m_prob_choose_min_var)) {
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lit = m_min_vars[m_rand(m_min_vars.size())];
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return true;
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}
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else if (min_break == UINT_MAX) {
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return false;
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}
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else {
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lit = c[m_rand(c.size())];
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return !m_tabu[lit.var()];
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}
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}
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void sls::flip() {
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literal lit;
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if (!pick_flip(lit)) return;
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SASSERT(value_at(lit, m_model) == l_false);
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m_model[lit.var()] = lit.sign()?l_true:l_false;
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SASSERT(value_at(lit, m_model) == l_true);
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unsigned_vector const& use1 = get_use(lit);
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unsigned sz = use1.size();
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for (unsigned i = 0; i < sz; ++i) {
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unsigned cl = use1[i];
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m_num_true[cl]++;
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SASSERT(m_num_true[cl] <= m_clauses[cl]->size());
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if (m_num_true[cl] == 1) m_false.remove(cl);
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}
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unsigned_vector const& use2 = get_use(~lit);
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sz = use2.size();
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for (unsigned i = 0; i < sz; ++i) {
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unsigned cl = use2[i];
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SASSERT(m_num_true[cl] > 0);
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m_num_true[cl]--;
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if (m_num_true[cl] == 0) m_false.insert(cl);
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}
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}
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};
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@ -41,18 +41,30 @@ namespace sat {
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solver& s;
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random_gen m_rand;
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unsigned m_max_tries;
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unsigned m_max_flips;
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index_set m_false;
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use_list m_use_list;
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vector<clause> m_clauses;
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unsigned m_prob_choose_min_var; // number between 0 and 99.
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ptr_vector<clause const> m_clauses; // vector of all clauses.
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index_set m_false; // clauses currently false
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vector<unsigned_vector> m_use_list; // use lists for literals
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unsigned_vector m_num_true; // per clause, count of # true literals
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svector<literal> m_min_vars; // literals with smallest break count
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model m_model; // current model
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clause_allocator m_alloc; // clause allocator
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clause_vector m_bin_clauses; // binary clauses
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svector<bool> m_tabu; // variables that cannot be swapped
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public:
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sls(solver& s);
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~sls();
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lbool operator()();
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lbool operator()(unsigned sz, literal const* tabu);
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private:
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bool local_search();
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bool_var pick_flip();
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void flip(bool_var v);
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void init(unsigned sz, literal const* tabu);
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void init_model(unsigned sz, literal const* tabu);
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void init_use();
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void init_clauses();
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bool pick_flip(literal& lit);
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void flip();
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unsigned get_break_count(literal lit, unsigned min_break);
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unsigned_vector const& get_use(literal lit);
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};
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};
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@ -135,6 +135,7 @@ namespace sat {
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friend class probing;
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friend class iff3_finder;
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friend class mus;
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friend class sls;
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friend struct mk_stat;
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public:
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solver(params_ref const & p, extension * ext);
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