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https://github.com/Z3Prover/z3
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1490 lines
55 KiB
C++
1490 lines
55 KiB
C++
/*++
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Copyright (c) 2011 Microsoft Corporation
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Module Name:
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sat_simplifier.cpp
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Abstract:
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SAT simplification procedures that use a "full" occurrence list:
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Subsumption, Blocked Clause Removal, Variable Elimination, ...
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Author:
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Leonardo de Moura (leonardo) 2011-05-24.
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Revision History:
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--*/
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#include"sat_simplifier.h"
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#include"sat_solver.h"
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#include"stopwatch.h"
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#include"trace.h"
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namespace sat {
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void use_list::init(unsigned num_vars) {
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m_use_list.reset();
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unsigned num_lits = 2 * num_vars;
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m_use_list.resize(num_lits);
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}
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void use_list::insert(clause & c) {
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unsigned sz = c.size();
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for (unsigned i = 0; i < sz; i++) {
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m_use_list[c[i].index()].insert(c);
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}
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}
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void use_list::erase(clause & c) {
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unsigned sz = c.size();
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for (unsigned i = 0; i < sz; i++) {
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m_use_list[c[i].index()].erase(c);
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}
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}
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void use_list::erase(clause & c, literal l) {
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unsigned sz = c.size();
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for (unsigned i = 0; i < sz; i++) {
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literal l2 = c[i];
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if (l2 != l)
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m_use_list[l2.index()].erase(c);
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}
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}
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simplifier::simplifier(solver & _s, params_ref const & p):
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s(_s),
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m_num_calls(0) {
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updt_params(p);
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reset_statistics();
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}
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simplifier::~simplifier() {
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}
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inline watch_list & simplifier::get_wlist(literal l) { return s.get_wlist(l); }
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inline watch_list const & simplifier::get_wlist(literal l) const { return s.get_wlist(l); }
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inline bool simplifier::is_external(bool_var v) const { return s.is_external(v); }
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inline bool simplifier::was_eliminated(bool_var v) const { return s.was_eliminated(v); }
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lbool simplifier::value(bool_var v) const { return s.value(v); }
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lbool simplifier::value(literal l) const { return s.value(l); }
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inline void simplifier::checkpoint() { s.checkpoint(); }
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void simplifier::register_clauses(clause_vector & cs) {
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std::stable_sort(cs.begin(), cs.end(), size_lt());
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clause_vector::iterator it = cs.begin();
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clause_vector::iterator end = cs.end();
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for (; it != end; ++it) {
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clause & c = *(*it);
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if (!c.frozen()) {
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m_use_list.insert(c);
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if (c.strengthened())
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m_sub_todo.insert(c);
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}
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}
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}
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inline void simplifier::remove_clause_core(clause & c) {
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unsigned sz = c.size();
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for (unsigned i = 0; i < sz; i++)
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insert_todo(c[i].var());
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m_sub_todo.erase(c);
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c.set_removed(true);
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TRACE("resolution_bug", tout << "del_clause: " << c << "\n";);
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m_need_cleanup = true;
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}
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inline void simplifier::remove_clause(clause & c) {
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remove_clause_core(c);
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m_use_list.erase(c);
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}
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inline void simplifier::remove_clause(clause & c, literal l) {
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remove_clause_core(c);
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m_use_list.erase(c, l);
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}
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inline void simplifier::remove_bin_clause_half(literal l1, literal l2, bool learned) {
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SASSERT(s.get_wlist(~l1).contains(watched(l2, learned)));
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s.get_wlist(~l1).erase(watched(l2, learned));
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}
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void simplifier::init_visited() {
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m_visited.reset();
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m_visited.resize(2*s.num_vars(), false);
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}
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void simplifier::free_memory() {
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m_use_list.finalize();
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m_sub_todo.finalize();
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m_sub_bin_todo.finalize();
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m_visited.finalize();
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m_bs_cs.finalize();
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m_bs_ls.finalize();
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}
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void simplifier::operator()(bool learned) {
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if (s.inconsistent())
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return;
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if (!m_subsumption && !m_elim_blocked_clauses && !m_resolution)
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return;
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CASSERT("sat_solver", s.check_invariant());
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TRACE("before_simplifier", s.display(tout););
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s.m_cleaner(true);
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m_last_sub_trail_sz = s.m_trail.size();
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TRACE("after_cleanup", s.display(tout););
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CASSERT("sat_solver", s.check_invariant());
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m_need_cleanup = false;
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m_use_list.init(s.num_vars());
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init_visited();
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if (learned)
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register_clauses(s.m_learned);
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register_clauses(s.m_clauses);
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if (!learned && (m_elim_blocked_clauses || m_elim_blocked_clauses_at == m_num_calls))
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elim_blocked_clauses();
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if (!learned)
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m_num_calls++;
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m_sub_counter = m_subsumption_limit;
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m_elim_counter = m_res_limit;
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unsigned old_num_elim_vars = m_num_elim_vars;
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do {
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if (m_subsumption)
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subsume();
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if (s.inconsistent())
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return;
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if (!learned && m_resolution)
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elim_vars();
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if (s.inconsistent())
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return;
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if (!m_subsumption || m_sub_counter < 0)
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break;
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}
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while (!m_sub_todo.empty());
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bool vars_eliminated = m_num_elim_vars > old_num_elim_vars;
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if (!m_need_cleanup) {
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if (vars_eliminated) {
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// must remove learned clauses with eliminated variables
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cleanup_clauses(s.m_learned, true, true);
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}
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CASSERT("sat_solver", s.check_invariant());
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TRACE("after_simplifier", s.display(tout); tout << "model_converter:\n"; s.m_mc.display(tout););
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free_memory();
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return;
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}
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cleanup_watches();
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cleanup_clauses(s.m_learned, true, vars_eliminated);
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cleanup_clauses(s.m_clauses, false, vars_eliminated);
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TRACE("after_simplifier", s.display(tout); tout << "model_converter:\n"; s.m_mc.display(tout););
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CASSERT("sat_solver", s.check_invariant());
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free_memory();
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}
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/**
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\brief Eliminate all ternary and clause watches.
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*/
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void simplifier::cleanup_watches() {
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vector<watch_list>::iterator it = s.m_watches.begin();
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vector<watch_list>::iterator end = s.m_watches.end();
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for (; it != end; ++it) {
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watch_list & wlist = *it;
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watch_list::iterator it2 = wlist.begin();
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watch_list::iterator itprev = it2;
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watch_list::iterator end2 = wlist.end();
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for (; it2 != end2; ++it2) {
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switch (it2->get_kind()) {
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case watched::TERNARY:
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case watched::CLAUSE:
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// consume
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break;
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default:
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*itprev = *it2;
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itprev++;
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break;
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}
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}
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wlist.set_end(itprev);
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}
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}
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void simplifier::cleanup_clauses(clause_vector & cs, bool learned, bool vars_eliminated) {
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clause_vector::iterator it = cs.begin();
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clause_vector::iterator it2 = it;
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clause_vector::iterator end = cs.end();
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for (; it != end; ++it) {
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clause & c = *(*it);
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if (c.was_removed()) {
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s.del_clause(c);
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continue;
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}
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if (learned && vars_eliminated) {
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unsigned sz = c.size();
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unsigned i;
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for (i = 0; i < sz; i++) {
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if (was_eliminated(c[i].var()))
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break;
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}
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if (i < sz) {
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s.del_clause(c);
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continue;
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}
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}
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if (cleanup_clause(c)) {
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s.del_clause(c);
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continue;
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}
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unsigned sz = c.size();
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if (sz == 0) {
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s.set_conflict(justification());
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return;
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}
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if (sz == 1) {
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s.assign(c[0], justification());
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s.del_clause(c);
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continue;
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}
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if (sz == 2) {
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s.mk_bin_clause(c[0], c[1], c.is_learned());
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s.del_clause(c);
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continue;
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}
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// clause became a problem clause
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if (learned && !c.is_learned()) {
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SASSERT(!c.frozen());
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s.m_clauses.push_back(&c);
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continue;
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}
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*it2 = *it;
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it2++;
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if (!c.frozen()) {
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if (sz == 3)
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s.attach_ter_clause(c);
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else
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s.attach_nary_clause(c);
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}
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}
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cs.set_end(it2);
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}
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void simplifier::mark_all_but(clause const & c, literal l) {
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unsigned sz = c.size();
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for (unsigned i = 0; i < sz; i++) {
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if (c[i] == l)
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continue;
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mark_visited(c[i]);
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}
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}
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void simplifier::unmark_all(clause const & c) {
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unsigned sz = c.size();
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for (unsigned i = 0; i < sz; i++)
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unmark_visited(c[i]);
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}
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/**
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\brief Return the variable in c with the minimal number positive+negative occurrences.
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*/
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bool_var simplifier::get_min_occ_var(clause const & c) const {
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literal l_best = c[0];
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unsigned best = m_use_list.get(l_best).size() + m_use_list.get(~l_best).size();
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unsigned sz = c.size();
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for (unsigned i = 1; i < sz; i++) {
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literal l = c[i];
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unsigned num = m_use_list.get(l).size() + m_use_list.get(~l).size();
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if (num < best) {
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l_best = l;
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best = num;
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}
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}
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return l_best.var();
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}
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/**
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If c1 subsumes c2, return true
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If c2 can self subsumed by c1, return true and store the literal that can be removed from c2 in l.
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Otherwise return false
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*/
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bool simplifier::subsumes1(clause const & c1, clause const & c2, literal & l) {
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unsigned sz2 = c2.size();
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for (unsigned i = 0; i < sz2; i++)
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mark_visited(c2[i]);
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bool r = true;
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l = null_literal;
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unsigned sz1 = c1.size();
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for (unsigned i = 0; i < sz1; i++) {
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if (!is_marked(c1[i])) {
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if (l == null_literal && is_marked(~c1[i])) {
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l = ~c1[i];
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}
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else {
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l = null_literal;
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r = false;
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break;
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}
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}
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}
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for (unsigned i = 0; i < sz2; i++)
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unmark_visited(c2[i]);
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return r;
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}
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/**
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\brief Return the clauses subsumed by c1 and the clauses that can be subsumed resolved using c1.
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The collections is populated using the use list of target.
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*/
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void simplifier::collect_subsumed1_core(clause const & c1, clause_vector & out, literal_vector & out_lits,
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literal target) {
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clause_use_list const & cs = m_use_list.get(target);
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clause_use_list::iterator it = cs.mk_iterator();
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while (!it.at_end()) {
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clause & c2 = it.curr();
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CTRACE("resolution_bug", c2.was_removed(), tout << "clause has been removed:\n" << c2 << "\n";);
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SASSERT(!c2.was_removed());
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if (&c2 != &c1 &&
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c1.size() <= c2.size() &&
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approx_subset(c1.approx(), c2.approx())) {
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m_sub_counter -= c1.size() + c2.size();
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literal l;
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if (subsumes1(c1, c2, l)) {
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out.push_back(&c2);
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out_lits.push_back(l);
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}
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}
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it.next();
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}
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}
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/**
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\brief Return the clauses subsumed by c1 and the clauses that can be subsumed resolved using c1.
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*/
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void simplifier::collect_subsumed1(clause const & c1, clause_vector & out, literal_vector & out_lits) {
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bool_var v = get_min_occ_var(c1);
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collect_subsumed1_core(c1, out, out_lits, literal(v, false));
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collect_subsumed1_core(c1, out, out_lits, literal(v, true));
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}
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/**
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\brief Perform backward subsumption and self-subsumption resolution using c.
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*/
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void simplifier::back_subsumption1(clause & c1) {
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m_bs_cs.reset();
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m_bs_ls.reset();
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collect_subsumed1(c1, m_bs_cs, m_bs_ls);
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SASSERT(m_bs_cs.size() == m_bs_ls.size());
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clause_vector::iterator it = m_bs_cs.begin();
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clause_vector::iterator end = m_bs_cs.end();
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literal_vector::iterator l_it = m_bs_ls.begin();
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for (; it != end; ++it, ++l_it) {
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clause & c2 = *(*it);
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if (*l_it == null_literal) {
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// c2 was subsumed
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if (c1.is_learned() && !c2.is_learned())
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c1.unset_learned();
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TRACE("subsumption", tout << c1 << " subsumed " << c2 << "\n";);
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remove_clause(c2);
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m_num_subsumed++;
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}
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else {
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// subsumption resolution
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TRACE("subsumption_resolution", tout << c1 << " sub-ref(" << *l_it << ") " << c2 << "\n";);
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elim_lit(c2, *l_it);
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m_num_sub_res++;
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TRACE("subsumption_resolution", tout << "result: " << c2 << "\n";);
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}
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if (s.inconsistent())
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break;
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}
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}
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void simplifier::back_subsumption1(literal l1, literal l2, bool learned) {
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m_dummy.set(l1, l2, learned);
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clause & c = *(m_dummy.get());
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back_subsumption1(c);
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}
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/**
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\brief Return the literal in c with the minimal number of occurrences.
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*/
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literal simplifier::get_min_occ_var0(clause const & c) const {
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literal l_best = c[0];
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unsigned best = m_use_list.get(l_best).size();
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unsigned sz = c.size();
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for (unsigned i = 1; i < sz; i++) {
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literal l = c[i];
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unsigned num = m_use_list.get(l).size();
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if (num < best) {
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l_best = l;
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best = num;
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}
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}
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return l_best;
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}
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/**
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If c1 subsumes c2, return true
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Otherwise return false
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*/
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bool simplifier::subsumes0(clause const & c1, clause const & c2) {
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unsigned sz2 = c2.size();
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for (unsigned i = 0; i < sz2; i++)
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mark_visited(c2[i]);
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bool r = true;
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unsigned sz1 = c1.size();
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for (unsigned i = 0; i < sz1; i++) {
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if (!is_marked(c1[i])) {
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r = false;
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break;
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}
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}
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for (unsigned i = 0; i < sz2; i++)
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unmark_visited(c2[i]);
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return r;
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}
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/**
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\brief Collect the clauses subsumed by c1 (using the occurrence list of target).
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*/
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void simplifier::collect_subsumed0_core(clause const & c1, clause_vector & out, literal target) {
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clause_use_list const & cs = m_use_list.get(target);
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clause_use_list::iterator it = cs.mk_iterator();
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while (!it.at_end()) {
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clause & c2 = it.curr();
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SASSERT(!c2.was_removed());
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if (&c2 != &c1 &&
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c1.size() <= c2.size() &&
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approx_subset(c1.approx(), c2.approx())) {
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m_sub_counter -= c1.size() + c2.size();
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if (subsumes0(c1, c2)) {
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out.push_back(&c2);
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}
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}
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it.next();
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}
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}
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/**
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\brief Collect the clauses subsumed by c1
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*/
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void simplifier::collect_subsumed0(clause const & c1, clause_vector & out) {
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literal l = get_min_occ_var0(c1);
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collect_subsumed0_core(c1, out, l);
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}
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/**
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\brief Perform backward subsumption using c1.
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*/
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void simplifier::back_subsumption0(clause & c1) {
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m_bs_cs.reset();
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collect_subsumed0(c1, m_bs_cs);
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clause_vector::iterator it = m_bs_cs.begin();
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clause_vector::iterator end = m_bs_cs.end();
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for (; it != end; ++it) {
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clause & c2 = *(*it);
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// c2 was subsumed
|
|
if (c1.is_learned() && !c2.is_learned())
|
|
c1.unset_learned();
|
|
TRACE("subsumption", tout << c1 << " subsumed " << c2 << "\n";);
|
|
remove_clause(c2);
|
|
m_num_subsumed++;
|
|
}
|
|
}
|
|
|
|
/**
|
|
\brief Eliminate false literals from c, and update occurrence lists
|
|
|
|
Return true if the clause is satisfied
|
|
*/
|
|
bool simplifier::cleanup_clause(clause & c) {
|
|
bool r = false;
|
|
unsigned sz = c.size();
|
|
unsigned j = 0;
|
|
for (unsigned i = 0; i < sz; i++) {
|
|
literal l = c[i];
|
|
switch (value(l)) {
|
|
case l_undef:
|
|
c[j] = l;
|
|
j++;
|
|
break;
|
|
case l_false:
|
|
m_need_cleanup = true;
|
|
m_use_list.get(l).erase_not_removed(c);
|
|
break;
|
|
case l_true:
|
|
r = true;
|
|
c[j] = l;
|
|
j++;
|
|
break;
|
|
}
|
|
}
|
|
c.shrink(j);
|
|
return r;
|
|
}
|
|
|
|
/**
|
|
\brief Eliminate false literals from c.
|
|
|
|
Return true if the clause is satisfied
|
|
*/
|
|
bool simplifier::cleanup_clause(literal_vector & c) {
|
|
unsigned sz = c.size();
|
|
unsigned j = 0;
|
|
for (unsigned i = 0; i < sz; i++) {
|
|
literal l = c[i];
|
|
switch (value(l)) {
|
|
case l_undef:
|
|
c[j] = l;
|
|
j++;
|
|
break;
|
|
case l_false:
|
|
break;
|
|
case l_true:
|
|
return true;
|
|
}
|
|
}
|
|
c.shrink(j);
|
|
return false;
|
|
}
|
|
|
|
inline void simplifier::propagate_unit(literal l) {
|
|
unsigned old_trail_sz = s.m_trail.size();
|
|
s.assign(l, justification());
|
|
s.propagate_core(false); // must not use propagate(), since s.m_clauses is not in a consistent state.
|
|
if (s.inconsistent())
|
|
return;
|
|
unsigned new_trail_sz = s.m_trail.size();
|
|
for (unsigned i = old_trail_sz; i < new_trail_sz; i++) {
|
|
literal l = s.m_trail[i];
|
|
{
|
|
// put clauses with literals assigned to false back into todo-list
|
|
clause_use_list & cs = m_use_list.get(~l);
|
|
clause_use_list::iterator it = cs.mk_iterator();
|
|
while (!it.at_end()) {
|
|
clause & c = it.curr();
|
|
it.next();
|
|
m_sub_todo.insert(c);
|
|
}
|
|
}
|
|
{
|
|
// erase satisfied clauses
|
|
clause_use_list & cs = m_use_list.get(l);
|
|
{
|
|
clause_use_list::iterator it = cs.mk_iterator();
|
|
while (!it.at_end()) {
|
|
clause & c = it.curr();
|
|
it.next();
|
|
remove_clause(c, l);
|
|
}
|
|
}
|
|
cs.reset();
|
|
}
|
|
}
|
|
}
|
|
|
|
void simplifier::elim_lit(clause & c, literal l) {
|
|
TRACE("elim_lit", tout << "processing: " << c << "\n";);
|
|
m_need_cleanup = true;
|
|
m_num_elim_lits++;
|
|
insert_todo(l.var());
|
|
c.elim(l);
|
|
clause_use_list & occurs = m_use_list.get(l);
|
|
occurs.erase_not_removed(c);
|
|
m_sub_counter -= occurs.size()/2;
|
|
if (cleanup_clause(c)) {
|
|
// clause was satisfied
|
|
TRACE("elim_lit", tout << "clause was satisfied\n";);
|
|
remove_clause(c);
|
|
return;
|
|
}
|
|
switch (c.size()) {
|
|
case 0:
|
|
TRACE("elim_lit", tout << "clause is empty\n";);
|
|
s.set_conflict(justification());
|
|
return;
|
|
case 1:
|
|
TRACE("elim_lit", tout << "clause became unit: " << c[0] << "\n";);
|
|
propagate_unit(c[0]);
|
|
remove_clause(c);
|
|
return;
|
|
case 2:
|
|
TRACE("elim_lit", tout << "clause became binary: " << c[0] << " " << c[1] << "\n";);
|
|
s.mk_bin_clause(c[0], c[1], c.is_learned());
|
|
m_sub_bin_todo.push_back(bin_clause(c[0], c[1], c.is_learned()));
|
|
remove_clause(c);
|
|
return;
|
|
default:
|
|
TRACE("elim_lit", tout << "result: " << c << "\n";);
|
|
m_sub_todo.insert(c);
|
|
return;
|
|
}
|
|
}
|
|
|
|
bool simplifier::subsume_with_binaries() {
|
|
unsigned init = s.m_rand(); // start in a random place, since subsumption can be aborted
|
|
unsigned num_lits = s.m_watches.size();
|
|
for (unsigned i = 0; i < num_lits; i++) {
|
|
unsigned l_idx = (i + init) % num_lits;
|
|
watch_list & wlist = get_wlist(to_literal(l_idx));
|
|
literal l = ~to_literal(l_idx);
|
|
// should not traverse wlist using iterators, since back_subsumption1 may add new binary clauses there
|
|
for (unsigned j = 0; j < wlist.size(); j++) {
|
|
watched w = wlist[j];
|
|
if (w.is_binary_clause()) {
|
|
literal l2 = w.get_literal();
|
|
if (l.index() < l2.index()) {
|
|
m_dummy.set(l, l2, w.is_learned());
|
|
clause & c = *(m_dummy.get());
|
|
back_subsumption1(c);
|
|
if (w.is_learned() && !c.is_learned()) {
|
|
SASSERT(wlist[j] == w);
|
|
TRACE("mark_not_learned_bug",
|
|
tout << "marking as not learned: " << l2 << " " << wlist[j].is_learned() << "\n";);
|
|
wlist[j].mark_not_learned();
|
|
mark_as_not_learned_core(get_wlist(~l2), l);
|
|
}
|
|
if (s.inconsistent())
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
if (m_sub_counter < 0)
|
|
break;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
void simplifier::mark_as_not_learned_core(watch_list & wlist, literal l2) {
|
|
watch_list::iterator it = wlist.begin();
|
|
watch_list::iterator end = wlist.end();
|
|
for (; it != end; ++it) {
|
|
if (it->is_binary_clause() && it->get_literal() == l2 && it->is_learned()) {
|
|
it->mark_not_learned();
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
void simplifier::mark_as_not_learned(literal l1, literal l2) {
|
|
mark_as_not_learned_core(get_wlist(~l1), l2);
|
|
mark_as_not_learned_core(get_wlist(~l2), l1);
|
|
}
|
|
|
|
struct bin_lt {
|
|
bool operator()(watched const & w1, watched const & w2) const {
|
|
if (!w1.is_binary_clause()) return false;
|
|
if (!w2.is_binary_clause()) return true;
|
|
unsigned l1_idx = w1.get_literal().index();
|
|
unsigned l2_idx = w2.get_literal().index();
|
|
if (l1_idx < l2_idx) return true;
|
|
if (l1_idx == l2_idx && !w1.is_learned() && w2.is_learned()) return true;
|
|
return false;
|
|
}
|
|
};
|
|
|
|
/**
|
|
\brief Eliminate duplicated binary clauses.
|
|
*/
|
|
void simplifier::elim_dup_bins() {
|
|
vector<watch_list>::iterator it = s.m_watches.begin();
|
|
vector<watch_list>::iterator end = s.m_watches.end();
|
|
#ifdef _TRACE
|
|
unsigned l_idx = 0;
|
|
#endif
|
|
unsigned elim = 0;
|
|
for (; it != end; ++it) {
|
|
checkpoint();
|
|
watch_list & wlist = *it;
|
|
std::stable_sort(wlist.begin(), wlist.end(), bin_lt());
|
|
literal last_lit = null_literal;
|
|
watch_list::iterator it2 = wlist.begin();
|
|
watch_list::iterator itprev = it2;
|
|
watch_list::iterator end2 = wlist.end();
|
|
for (; it2 != end2; ++it2) {
|
|
if (!it2->is_binary_clause()) {
|
|
*itprev = *it2;
|
|
itprev++;
|
|
continue;
|
|
}
|
|
if (it2->get_literal() == last_lit) {
|
|
TRACE("subsumption", tout << "eliminating: " << ~to_literal(l_idx)
|
|
<< " " << it2->get_literal() << "\n";);
|
|
elim++;
|
|
}
|
|
else {
|
|
last_lit = it2->get_literal();
|
|
*itprev = *it2;
|
|
itprev++;
|
|
}
|
|
}
|
|
wlist.set_end(itprev);
|
|
TRACE_CODE(l_idx++;);
|
|
}
|
|
m_num_subsumed += elim/2; // each binary clause is "eliminated" twice.
|
|
}
|
|
|
|
struct simplifier::subsumption_report {
|
|
simplifier & m_simplifier;
|
|
stopwatch m_watch;
|
|
unsigned m_num_subsumed;
|
|
unsigned m_num_sub_res;
|
|
subsumption_report(simplifier & s):
|
|
m_simplifier(s),
|
|
m_num_subsumed(s.m_num_subsumed),
|
|
m_num_sub_res(s.m_num_sub_res) {
|
|
m_watch.start();
|
|
}
|
|
|
|
~subsumption_report() {
|
|
m_watch.stop();
|
|
IF_VERBOSE(SAT_VB_LVL,
|
|
verbose_stream() << " (sat-subsumer :subsumed "
|
|
<< (m_simplifier.m_num_subsumed - m_num_subsumed)
|
|
<< " :subsumption-resolution " << (m_simplifier.m_num_sub_res - m_num_sub_res)
|
|
<< " :threshold " << m_simplifier.m_sub_counter
|
|
<< mem_stat()
|
|
<< " :time " << std::fixed << std::setprecision(2) << m_watch.get_seconds() << ")\n";);
|
|
}
|
|
};
|
|
|
|
void simplifier::subsume() {
|
|
subsumption_report rpt(*this);
|
|
elim_dup_bins();
|
|
subsume_with_binaries();
|
|
TRACE("subsumption_bug", s.display(tout););
|
|
while (true) {
|
|
TRACE("subsumption", tout << "sub_todo size: " << m_sub_todo.size() << "\n";);
|
|
|
|
m_sub_counter -= m_sub_bin_todo.size();
|
|
while (!m_sub_bin_todo.empty()) {
|
|
checkpoint();
|
|
m_dummy.set(m_sub_bin_todo.back());
|
|
m_sub_bin_todo.pop_back();
|
|
clause & c = *(m_dummy.get());
|
|
bool was_learned = c.is_learned();
|
|
back_subsumption1(c);
|
|
if (was_learned && !c.is_learned()) {
|
|
mark_as_not_learned(c[0], c[1]);
|
|
}
|
|
}
|
|
|
|
checkpoint();
|
|
|
|
TRACE("subsumption_bug", s.display(tout););
|
|
|
|
if (m_sub_todo.empty()) {
|
|
m_last_sub_trail_sz = s.m_trail.size();
|
|
break;
|
|
}
|
|
|
|
if (m_sub_counter < 0)
|
|
break;
|
|
|
|
clause & c = m_sub_todo.erase();
|
|
c.unmark_strengthened();
|
|
m_sub_counter--;
|
|
TRACE("subsumption", tout << "next: " << c << "\n";);
|
|
if (s.m_trail.size() > m_last_sub_trail_sz) {
|
|
if (cleanup_clause(c)) {
|
|
remove_clause(c);
|
|
continue;
|
|
}
|
|
unsigned sz = c.size();
|
|
if (sz == 0) {
|
|
s.set_conflict(justification());
|
|
return;
|
|
}
|
|
if (sz == 1) {
|
|
propagate_unit(c[0]);
|
|
remove_clause(c);
|
|
continue;
|
|
}
|
|
if (sz == 2) {
|
|
TRACE("subsumption", tout << "clause became binary: " << c << "\n";);
|
|
s.mk_bin_clause(c[0], c[1], c.is_learned());
|
|
m_sub_bin_todo.push_back(bin_clause(c[0], c[1], c.is_learned()));
|
|
remove_clause(c);
|
|
continue;
|
|
}
|
|
}
|
|
TRACE("subsumption", tout << "using: " << c << "\n";);
|
|
back_subsumption1(c);
|
|
}
|
|
}
|
|
|
|
struct simplifier::blocked_clause_elim {
|
|
class literal_lt {
|
|
use_list const & m_use_list;
|
|
vector<watch_list> const & m_watches;
|
|
public:
|
|
literal_lt(use_list const & l, vector<watch_list> const & ws):m_use_list(l), m_watches(ws) {}
|
|
|
|
unsigned weight(unsigned l_idx) const {
|
|
return 2*m_use_list.get(~to_literal(l_idx)).size() + m_watches[l_idx].size();
|
|
}
|
|
|
|
bool operator()(unsigned l_idx1, unsigned l_idx2) const {
|
|
return weight(l_idx1) < weight(l_idx2);
|
|
}
|
|
};
|
|
|
|
class queue {
|
|
heap<literal_lt> m_queue;
|
|
public:
|
|
queue(use_list const & l, vector<watch_list> const & ws):m_queue(128, literal_lt(l, ws)) {}
|
|
void insert(literal l) {
|
|
unsigned idx = l.index();
|
|
m_queue.reserve(idx + 1);
|
|
SASSERT(!m_queue.contains(idx));
|
|
m_queue.insert(idx);
|
|
}
|
|
void decreased(literal l) {
|
|
unsigned idx = l.index();
|
|
if (m_queue.contains(idx))
|
|
m_queue.decreased(idx);
|
|
else
|
|
m_queue.insert(idx);
|
|
}
|
|
literal next() { SASSERT(!empty()); return to_literal(m_queue.erase_min()); }
|
|
bool empty() const { return m_queue.empty(); }
|
|
};
|
|
|
|
simplifier & s;
|
|
int m_counter;
|
|
model_converter & mc;
|
|
queue m_queue;
|
|
clause_vector m_to_remove;
|
|
|
|
blocked_clause_elim(simplifier & _s, unsigned limit, model_converter & _mc, use_list & l,
|
|
vector<watch_list> & wlist):
|
|
s(_s),
|
|
m_counter(limit),
|
|
mc(_mc),
|
|
m_queue(l, wlist) {
|
|
}
|
|
|
|
void insert(literal l) {
|
|
bool_var v = l.var();
|
|
if (s.is_external(v) || s.was_eliminated(v))
|
|
return;
|
|
m_queue.insert(l);
|
|
}
|
|
|
|
void operator()(unsigned num_vars) {
|
|
for (bool_var v = 0; v < num_vars; v++) {
|
|
insert(literal(v, false));
|
|
insert(literal(v, true));
|
|
}
|
|
while (!m_queue.empty()) {
|
|
s.checkpoint();
|
|
if (m_counter < 0)
|
|
return;
|
|
literal l = m_queue.next();
|
|
process(l);
|
|
}
|
|
}
|
|
|
|
void process(literal l) {
|
|
TRACE("blocked_clause", tout << "processing: " << l << "\n";);
|
|
model_converter::entry * new_entry = 0;
|
|
{
|
|
m_to_remove.reset();
|
|
{
|
|
clause_use_list & occs = s.m_use_list.get(l);
|
|
clause_use_list::iterator it = occs.mk_iterator();
|
|
while (!it.at_end()) {
|
|
clause & c = it.curr();
|
|
m_counter -= c.size();
|
|
SASSERT(c.contains(l));
|
|
s.mark_all_but(c, l);
|
|
if (all_tautology(l)) {
|
|
TRACE("blocked_clause", tout << "new blocked clause: " << c << "\n";);
|
|
if (new_entry == 0)
|
|
new_entry = &(mc.mk(model_converter::BLOCK_LIT, l.var()));
|
|
m_to_remove.push_back(&c);
|
|
s.m_num_blocked_clauses++;
|
|
mc.insert(*new_entry, c);
|
|
unsigned sz = c.size();
|
|
for (unsigned i = 0; i < sz; i++) {
|
|
if (c[i] != l)
|
|
m_queue.decreased(~c[i]);
|
|
}
|
|
}
|
|
s.unmark_all(c);
|
|
it.next();
|
|
}
|
|
}
|
|
clause_vector::iterator it = m_to_remove.begin();
|
|
clause_vector::iterator end = m_to_remove.end();
|
|
for (; it != end; ++it) {
|
|
s.remove_clause(*(*it));
|
|
}
|
|
}
|
|
{
|
|
watch_list & wlist = s.get_wlist(~l);
|
|
m_counter -= wlist.size();
|
|
watch_list::iterator it = wlist.begin();
|
|
watch_list::iterator it2 = it;
|
|
watch_list::iterator end = wlist.end();
|
|
for (; it != end; ++it) {
|
|
if (!it->is_binary_clause()) {
|
|
*it2 = *it;
|
|
it2++;
|
|
continue;
|
|
}
|
|
literal l2 = it->get_literal();
|
|
s.mark_visited(l2);
|
|
if (all_tautology(l)) {
|
|
if (new_entry == 0)
|
|
new_entry = &(mc.mk(model_converter::BLOCK_LIT, l.var()));
|
|
TRACE("blocked_clause", tout << "new blocked clause: " << l2 << " " << l << "\n";);
|
|
s.remove_bin_clause_half(l2, l, it->is_learned());
|
|
s.m_num_blocked_clauses++;
|
|
m_queue.decreased(~l2);
|
|
mc.insert(*new_entry, l, l2);
|
|
}
|
|
else {
|
|
*it2 = *it;
|
|
it2++;
|
|
}
|
|
s.unmark_visited(l2);
|
|
}
|
|
wlist.set_end(it2);
|
|
}
|
|
}
|
|
|
|
bool all_tautology(literal l) {
|
|
{
|
|
watch_list & wlist = s.get_wlist(l);
|
|
m_counter -= wlist.size();
|
|
watch_list::iterator it = wlist.begin();
|
|
watch_list::iterator end = wlist.end();
|
|
for (; it != end; ++it) {
|
|
if (!it->is_binary_non_learned_clause())
|
|
continue;
|
|
if (!s.is_marked(~it->get_literal()))
|
|
return false;
|
|
}
|
|
}
|
|
{
|
|
clause_use_list & neg_occs = s.m_use_list.get(~l);
|
|
clause_use_list::iterator it = neg_occs.mk_iterator();
|
|
while (!it.at_end()) {
|
|
clause & c = it.curr();
|
|
m_counter -= c.size();
|
|
unsigned sz = c.size();
|
|
unsigned i;
|
|
for (i = 0; i < sz; i++) {
|
|
if (s.is_marked(~c[i]))
|
|
break;
|
|
}
|
|
if (i == sz)
|
|
return false;
|
|
it.next();
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
};
|
|
|
|
struct simplifier::blocked_cls_report {
|
|
simplifier & m_simplifier;
|
|
stopwatch m_watch;
|
|
unsigned m_num_blocked_clauses;
|
|
blocked_cls_report(simplifier & s):
|
|
m_simplifier(s),
|
|
m_num_blocked_clauses(s.m_num_blocked_clauses) {
|
|
m_watch.start();
|
|
}
|
|
|
|
~blocked_cls_report() {
|
|
m_watch.stop();
|
|
IF_VERBOSE(SAT_VB_LVL,
|
|
verbose_stream() << " (sat-blocked-clauses :elim-blocked-clauses "
|
|
<< (m_simplifier.m_num_blocked_clauses - m_num_blocked_clauses)
|
|
<< mem_stat()
|
|
<< " :time " << std::fixed << std::setprecision(2) << m_watch.get_seconds() << ")\n";);
|
|
}
|
|
};
|
|
|
|
void simplifier::elim_blocked_clauses() {
|
|
TRACE("blocked_clause_bug", tout << "trail: " << s.m_trail.size() << "\n"; s.display_watches(tout); s.display(tout););
|
|
blocked_cls_report rpt(*this);
|
|
blocked_clause_elim elim(*this, m_blocked_clause_limit, s.m_mc, m_use_list, s.m_watches);
|
|
elim(s.num_vars());
|
|
}
|
|
|
|
unsigned simplifier::get_num_non_learned_bin(literal l) const {
|
|
unsigned r = 0;
|
|
watch_list const & wlist = get_wlist(~l);
|
|
watch_list::const_iterator it = wlist.begin();
|
|
watch_list::const_iterator end = wlist.end();
|
|
for (; it != end; ++it) {
|
|
if (it->is_binary_non_learned_clause())
|
|
r++;
|
|
}
|
|
return r;
|
|
}
|
|
|
|
unsigned simplifier::get_to_elim_cost(bool_var v) const {
|
|
literal pos_l(v, false);
|
|
literal neg_l(v, true);
|
|
unsigned num_pos = m_use_list.get(pos_l).size();
|
|
unsigned num_neg = m_use_list.get(neg_l).size();
|
|
unsigned num_bin_pos = get_num_non_learned_bin(pos_l);
|
|
unsigned num_bin_neg = get_num_non_learned_bin(neg_l);
|
|
unsigned cost = 2 * num_pos * num_neg + num_pos * num_bin_neg + num_neg * num_bin_pos;
|
|
CTRACE("elim_vars_detail", cost == 0, tout << v << " num_pos: " << num_pos << " num_neg: " << num_neg << " num_bin_pos: " << num_bin_pos
|
|
<< " num_bin_neg: " << num_bin_neg << " cost: " << cost << "\n";);
|
|
return cost;
|
|
}
|
|
|
|
typedef std::pair<bool_var, unsigned> bool_var_and_cost;
|
|
|
|
struct bool_var_and_cost_lt {
|
|
bool operator()(bool_var_and_cost const & p1, bool_var_and_cost const & p2) const { return p1.second < p2.second; }
|
|
};
|
|
|
|
void simplifier::order_vars_for_elim(bool_var_vector & r) {
|
|
svector<bool_var_and_cost> tmp;
|
|
bool_var_set::iterator it = m_elim_todo.begin();
|
|
bool_var_set::iterator end = m_elim_todo.end();
|
|
for (; it != end; ++it) {
|
|
bool_var v = *it;
|
|
if (is_external(v))
|
|
continue;
|
|
if (was_eliminated(v))
|
|
continue;
|
|
if (value(v) != l_undef)
|
|
continue;
|
|
unsigned c = get_to_elim_cost(v);
|
|
tmp.push_back(bool_var_and_cost(v, c));
|
|
}
|
|
m_elim_todo.reset();
|
|
std::stable_sort(tmp.begin(), tmp.end(), bool_var_and_cost_lt());
|
|
TRACE("elim_vars",
|
|
svector<bool_var_and_cost>::iterator it = tmp.begin();
|
|
svector<bool_var_and_cost>::iterator end = tmp.end();
|
|
for (; it != end; ++it) {
|
|
tout << "(" << it->first << ", " << it->second << ") ";
|
|
}
|
|
tout << "\n";);
|
|
svector<bool_var_and_cost>::iterator it2 = tmp.begin();
|
|
svector<bool_var_and_cost>::iterator end2 = tmp.end();
|
|
for (; it2 != end2; ++it2) {
|
|
r.push_back(it2->first);
|
|
}
|
|
}
|
|
|
|
/**
|
|
\brief Collect clauses and binary clauses containing l.
|
|
*/
|
|
void simplifier::collect_clauses(literal l, clause_wrapper_vector & r) {
|
|
clause_use_list const & cs = m_use_list.get(l);
|
|
clause_use_list::iterator it = cs.mk_iterator();
|
|
while (!it.at_end()) {
|
|
r.push_back(clause_wrapper(it.curr()));
|
|
SASSERT(r.back().size() == it.curr().size());
|
|
it.next();
|
|
}
|
|
|
|
watch_list & wlist = get_wlist(~l);
|
|
watch_list::iterator it2 = wlist.begin();
|
|
watch_list::iterator end2 = wlist.end();
|
|
for (; it2 != end2; ++it2) {
|
|
if (it2->is_binary_non_learned_clause()) {
|
|
r.push_back(clause_wrapper(l, it2->get_literal()));
|
|
SASSERT(r.back().size() == 2);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
\brief Resolve clauses c1 and c2.
|
|
c1 must contain l.
|
|
c2 must contain ~l.
|
|
Store result in r.
|
|
Return false if the result is a tautology
|
|
*/
|
|
bool simplifier::resolve(clause_wrapper const & c1, clause_wrapper const & c2, literal l, literal_vector & r) {
|
|
CTRACE("resolve_bug", !c1.contains(l), tout << c1 << "\n" << c2 << "\nl: " << l << "\n";);
|
|
SASSERT(c1.contains(l));
|
|
SASSERT(c2.contains(~l));
|
|
bool res = true;
|
|
unsigned sz = c1.size();
|
|
m_elim_counter -= sz;
|
|
for (unsigned i = 0; i < sz; i++) {
|
|
literal l2 = c1[i];
|
|
if (l == l2)
|
|
continue;
|
|
m_visited[l2.index()] = true;
|
|
r.push_back(l2);
|
|
}
|
|
|
|
literal not_l = ~l;
|
|
sz = c2.size();
|
|
m_elim_counter -= sz;
|
|
for (unsigned i = 0; i < sz; i++) {
|
|
literal l2 = c2[i];
|
|
if (not_l == l2)
|
|
continue;
|
|
if (m_visited[(~l2).index()]) {
|
|
res = false;
|
|
break;
|
|
}
|
|
if (!m_visited[l2.index()])
|
|
r.push_back(l2);
|
|
}
|
|
|
|
sz = c1.size();
|
|
for (unsigned i = 0; i < sz; i++) {
|
|
literal l2 = c1[i];
|
|
if (l == l2)
|
|
continue;
|
|
m_visited[l2.index()] = false;
|
|
}
|
|
|
|
return res;
|
|
}
|
|
|
|
void simplifier::save_clauses(model_converter::entry & mc_entry, clause_wrapper_vector const & cs) {
|
|
model_converter & mc = s.m_mc;
|
|
clause_wrapper_vector::const_iterator it = cs.begin();
|
|
clause_wrapper_vector::const_iterator end = cs.end();
|
|
for (; it != end; ++it)
|
|
mc.insert(mc_entry, *it);
|
|
}
|
|
|
|
void simplifier::add_non_learned_binary_clause(literal l1, literal l2) {
|
|
watch_list & wlist1 = s.m_watches[(~l1).index()];
|
|
watch_list & wlist2 = s.m_watches[(~l2).index()];
|
|
watch_list::iterator it1 = wlist1.begin();
|
|
watch_list::iterator end1 = wlist1.end();
|
|
for (; it1 != end1; ++it1) {
|
|
if (it1->is_binary_clause() && it1->get_literal() == l2) {
|
|
*it1 = watched(l2, false);
|
|
watch_list::iterator it2 = wlist2.begin();
|
|
watch_list::iterator end2 = wlist2.end();
|
|
for (; it2 != end2; ++it2) {
|
|
if (it2->is_binary_clause() && it2->get_literal() == l1) {
|
|
*it2 = watched(l1, false);
|
|
break;
|
|
}
|
|
}
|
|
CTRACE("resolve_bug", it2 == end2,
|
|
tout << ~l1 << " -> ";
|
|
display(tout, s.m_cls_allocator, wlist1); tout << "\n" << ~l2 << " -> ";
|
|
display(tout, s.m_cls_allocator, wlist2); tout << "\n";);
|
|
SASSERT(it2 != end2);
|
|
return;
|
|
}
|
|
}
|
|
wlist1.push_back(watched(l2, false));
|
|
wlist2.push_back(watched(l1, false));
|
|
}
|
|
|
|
/**
|
|
\brief Eliminate the binary clauses watched by l, when l.var() is being eliminated
|
|
*/
|
|
void simplifier::remove_bin_clauses(literal l) {
|
|
watch_list & wlist = get_wlist(~l);
|
|
watch_list::iterator it = wlist.begin();
|
|
watch_list::iterator end = wlist.end();
|
|
for (; it != end; ++it) {
|
|
if (it->is_binary_clause()) {
|
|
literal l2 = it->get_literal();
|
|
watch_list & wlist2 = get_wlist(~l2);
|
|
watch_list::iterator it2 = wlist2.begin();
|
|
watch_list::iterator itprev = it2;
|
|
watch_list::iterator end2 = wlist2.end();
|
|
for (; it2 != end2; ++it2) {
|
|
if (it2->is_binary_clause() && it2->get_literal() == l) {
|
|
TRACE("bin_clause_bug", tout << "removing: " << l << " " << it2->get_literal() << "\n";);
|
|
continue;
|
|
}
|
|
*itprev = *it2;
|
|
itprev++;
|
|
}
|
|
wlist2.set_end(itprev);
|
|
}
|
|
}
|
|
TRACE("bin_clause_bug", tout << "collapsing watch_list of: " << l << "\n";);
|
|
wlist.finalize();
|
|
}
|
|
|
|
/**
|
|
\brief Eliminate the clauses where the variable being eliminated occur.
|
|
*/
|
|
void simplifier::remove_clauses(clause_use_list const & cs, literal l) {
|
|
clause_use_list::iterator it = cs.mk_iterator();
|
|
while (!it.at_end()) {
|
|
clause & c = it.curr();
|
|
it.next();
|
|
SASSERT(c.contains(l));
|
|
c.set_removed(true);
|
|
m_use_list.erase(c, l);
|
|
m_sub_todo.erase(c);
|
|
TRACE("resolution_bug", tout << "del_clause (elim_var): " << c << "\n";);
|
|
m_need_cleanup = true;
|
|
}
|
|
}
|
|
|
|
bool simplifier::try_eliminate(bool_var v) {
|
|
TRACE("resolution_bug", tout << "processing: " << v << "\n";);
|
|
if (value(v) != l_undef)
|
|
return false;
|
|
|
|
literal pos_l(v, false);
|
|
literal neg_l(v, true);
|
|
unsigned num_bin_pos = get_num_non_learned_bin(pos_l);
|
|
unsigned num_bin_neg = get_num_non_learned_bin(neg_l);
|
|
clause_use_list & pos_occs = m_use_list.get(pos_l);
|
|
clause_use_list & neg_occs = m_use_list.get(neg_l);
|
|
unsigned num_pos = pos_occs.size() + num_bin_pos;
|
|
unsigned num_neg = neg_occs.size() + num_bin_neg;
|
|
m_elim_counter -= num_pos + num_neg;
|
|
|
|
TRACE("resolution", tout << v << " num_pos: " << num_pos << " neg_pos: " << num_neg << "\n";);
|
|
|
|
if (num_pos >= m_res_occ_cutoff && num_neg >= m_res_occ_cutoff)
|
|
return false;
|
|
|
|
unsigned before_lits = num_bin_pos*2 + num_bin_neg*2;
|
|
|
|
{
|
|
clause_use_list::iterator it = pos_occs.mk_iterator();
|
|
while (!it.at_end()) {
|
|
before_lits += it.curr().size();
|
|
it.next();
|
|
}
|
|
}
|
|
|
|
{
|
|
clause_use_list::iterator it2 = neg_occs.mk_iterator();
|
|
while (!it2.at_end()) {
|
|
before_lits += it2.curr().size();
|
|
it2.next();
|
|
}
|
|
}
|
|
|
|
TRACE("resolution", tout << v << " num_pos: " << num_pos << " neg_pos: " << num_neg << " before_lits: " << before_lits << "\n";);
|
|
|
|
if (num_pos >= m_res_occ_cutoff3 && num_neg >= m_res_occ_cutoff3 && before_lits > m_res_lit_cutoff3 && s.m_clauses.size() > m_res_cls_cutoff2)
|
|
return false;
|
|
if (num_pos >= m_res_occ_cutoff2 && num_neg >= m_res_occ_cutoff2 && before_lits > m_res_lit_cutoff2 &&
|
|
s.m_clauses.size() > m_res_cls_cutoff1 && s.m_clauses.size() <= m_res_cls_cutoff2)
|
|
return false;
|
|
if (num_pos >= m_res_occ_cutoff1 && num_neg >= m_res_occ_cutoff1 && before_lits > m_res_lit_cutoff1 &&
|
|
s.m_clauses.size() <= m_res_cls_cutoff1)
|
|
return false;
|
|
|
|
m_pos_cls.reset();
|
|
m_neg_cls.reset();
|
|
collect_clauses(pos_l, m_pos_cls);
|
|
collect_clauses(neg_l, m_neg_cls);
|
|
|
|
m_elim_counter -= num_pos * num_neg + before_lits;
|
|
|
|
TRACE("resolution_detail", tout << "collecting number of after_clauses\n";);
|
|
unsigned before_clauses = num_pos + num_neg;
|
|
unsigned after_clauses = 0;
|
|
clause_wrapper_vector::iterator it1 = m_pos_cls.begin();
|
|
clause_wrapper_vector::iterator end1 = m_pos_cls.end();
|
|
for (; it1 != end1; ++it1) {
|
|
clause_wrapper_vector::iterator it2 = m_neg_cls.begin();
|
|
clause_wrapper_vector::iterator end2 = m_neg_cls.end();
|
|
for (; it2 != end2; ++it2) {
|
|
m_new_cls.reset();
|
|
if (resolve(*it1, *it2, pos_l, m_new_cls)) {
|
|
TRACE("resolution_detail", tout << *it1 << "\n" << *it2 << "\n-->\n";
|
|
for (unsigned i = 0; i < m_new_cls.size(); i++) tout << m_new_cls[i] << " "; tout << "\n";);
|
|
after_clauses++;
|
|
if (after_clauses > before_clauses) {
|
|
TRACE("resolution", tout << "too many after clauses: " << after_clauses << "\n";);
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
TRACE("resolution", tout << "found var to eliminate, before: " << before_clauses << " after: " << after_clauses << "\n";);
|
|
|
|
// eliminate variable
|
|
model_converter::entry & mc_entry = s.m_mc.mk(model_converter::ELIM_VAR, v);
|
|
save_clauses(mc_entry, m_pos_cls);
|
|
save_clauses(mc_entry, m_neg_cls);
|
|
s.m_eliminated[v] = true;
|
|
remove_bin_clauses(pos_l);
|
|
remove_bin_clauses(neg_l);
|
|
remove_clauses(pos_occs, pos_l);
|
|
remove_clauses(neg_occs, neg_l);
|
|
pos_occs.reset();
|
|
neg_occs.reset();
|
|
|
|
m_elim_counter -= num_pos * num_neg + before_lits;
|
|
|
|
it1 = m_pos_cls.begin();
|
|
end1 = m_pos_cls.end();
|
|
for (; it1 != end1; ++it1) {
|
|
clause_wrapper_vector::iterator it2 = m_neg_cls.begin();
|
|
clause_wrapper_vector::iterator end2 = m_neg_cls.end();
|
|
for (; it2 != end2; ++it2) {
|
|
m_new_cls.reset();
|
|
if (!resolve(*it1, *it2, pos_l, m_new_cls))
|
|
continue;
|
|
TRACE("resolution_new_cls", tout << *it1 << "\n" << *it2 << "\n-->\n" << m_new_cls << "\n";);
|
|
if (cleanup_clause(m_new_cls))
|
|
continue; // clause is already satisfied.
|
|
switch (m_new_cls.size()) {
|
|
case 0:
|
|
s.set_conflict(justification());
|
|
break;
|
|
case 1:
|
|
propagate_unit(m_new_cls[0]);
|
|
break;
|
|
case 2:
|
|
s.m_stats.m_mk_bin_clause++;
|
|
add_non_learned_binary_clause(m_new_cls[0], m_new_cls[1]);
|
|
back_subsumption1(m_new_cls[0], m_new_cls[1], false);
|
|
break;
|
|
default:
|
|
if (m_new_cls.size() == 3)
|
|
s.m_stats.m_mk_ter_clause++;
|
|
else
|
|
s.m_stats.m_mk_clause++;
|
|
clause * new_c = s.m_cls_allocator.mk_clause(m_new_cls.size(), m_new_cls.c_ptr(), false);
|
|
s.m_clauses.push_back(new_c);
|
|
m_use_list.insert(*new_c);
|
|
if (m_sub_counter > 0)
|
|
back_subsumption1(*new_c);
|
|
else
|
|
back_subsumption0(*new_c);
|
|
break;
|
|
}
|
|
if (s.inconsistent())
|
|
return true;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
struct simplifier::elim_var_report {
|
|
simplifier & m_simplifier;
|
|
stopwatch m_watch;
|
|
unsigned m_num_elim_vars;
|
|
elim_var_report(simplifier & s):
|
|
m_simplifier(s),
|
|
m_num_elim_vars(s.m_num_elim_vars) {
|
|
m_watch.start();
|
|
}
|
|
|
|
~elim_var_report() {
|
|
m_watch.stop();
|
|
IF_VERBOSE(SAT_VB_LVL,
|
|
verbose_stream() << " (sat-resolution :elim-bool-vars "
|
|
<< (m_simplifier.m_num_elim_vars - m_num_elim_vars)
|
|
<< " :threshold " << m_simplifier.m_elim_counter
|
|
<< mem_stat()
|
|
<< " :time " << std::fixed << std::setprecision(2) << m_watch.get_seconds() << ")\n";);
|
|
}
|
|
};
|
|
|
|
void simplifier::elim_vars() {
|
|
elim_var_report rpt(*this);
|
|
bool_var_vector vars;
|
|
order_vars_for_elim(vars);
|
|
|
|
bool_var_vector::iterator it = vars.begin();
|
|
bool_var_vector::iterator end = vars.end();
|
|
for (; it != end; ++it) {
|
|
checkpoint();
|
|
if (m_elim_counter < 0)
|
|
return;
|
|
bool_var v = *it;
|
|
if (try_eliminate(v)) {
|
|
m_num_elim_vars++;
|
|
}
|
|
}
|
|
|
|
m_pos_cls.finalize();
|
|
m_neg_cls.finalize();
|
|
m_new_cls.finalize();
|
|
}
|
|
|
|
void simplifier::updt_params(params_ref const & p) {
|
|
m_elim_blocked_clauses = p.get_bool(":elim-blocked-clauses", false);
|
|
m_elim_blocked_clauses_at = p.get_uint(":elim-blocked-clauses-at", 2);
|
|
m_blocked_clause_limit = p.get_uint(":blocked-clause-limit", 100000000);
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m_resolution = p.get_bool(":resolution", true);
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m_res_limit = p.get_uint(":resolution-limit", 500000000);
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m_res_occ_cutoff = p.get_uint(":res-occ-cutoff", 10);
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m_res_occ_cutoff1 = p.get_uint(":res-occ-cutoff-range1", 8);
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m_res_occ_cutoff2 = p.get_uint(":res-occ-cutoff-range2", 5);
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m_res_occ_cutoff3 = p.get_uint(":res-occ-cutoff-range3", 3);
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m_res_lit_cutoff1 = p.get_uint(":res-lit-cutoff-range1", 700);
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m_res_lit_cutoff2 = p.get_uint(":res-lit-cutoff-range2", 400);
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m_res_lit_cutoff3 = p.get_uint(":res-lit-cutoff-range3", 300);
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m_res_cls_cutoff1 = p.get_uint(":res-cls-cutoff1", 100000);
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m_res_cls_cutoff2 = p.get_uint(":res-cls-cutoff2", 700000);
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m_subsumption = p.get_bool(":subsumption", true);
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m_subsumption_limit = p.get_uint(":subsumption-limit", 100000000);
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}
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void simplifier::collect_param_descrs(param_descrs & r) {
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r.insert(":elim-blocked-clauses", CPK_BOOL, "(default: false) eliminate blocked clauses.");
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r.insert(":elim-blocked-clauses-at", CPK_UINT, "(default: 2) eliminate blocked clauses only once at the given simplification round.");
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r.insert(":blocked-clause-limit", CPK_UINT, "(default: 100000000) maximum number of literals visited during blocked clause elimination.");
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r.insert(":resolution", CPK_BOOL, "(default: true) eliminate boolean variables using resolution.");
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r.insert(":resolution-limit", CPK_UINT, "(default: 500000000) approx. maximum number of literals visited during variable elimination.");
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r.insert(":res-occ-cutoff", CPK_UINT, "(default: 10) first cutoff (on number of positive/negative occurrences) for Boolean variable elimination.");
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r.insert(":res-occ-cutoff-range1", CPK_UINT, "(default: 8) second cutoff (number of positive/negative occurrences) for Boolean variable elimination, for problems containing less than :res-cls-cutoff1 clauses.");
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r.insert(":res-occ-cutoff-range2", CPK_UINT, "(default: 5) second cutoff (number of positive/negative occurrences) for Boolean variable elimination, for problems containing more than :res-cls-cutoff1 and less than :res-cls-cutoff2.");
|
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r.insert(":res-occ-cutoff-range3", CPK_UINT, "(default: 3) second cutoff (number of positive/negative occurrences) for Boolean variable elimination, for problems containing more than :res-cls-cutoff2.");
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|
|
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r.insert(":res-lit-cutoff-range1", CPK_UINT, "(default: 700) second cutoff (total number of literals) for Boolean variable elimination, for problems containing less than :res-cls-cutoff1 clauses.");
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|
r.insert(":res-lit-cutoff-range2", CPK_UINT, "(default: 400) second cutoff (total number of literals) for Boolean variable elimination, for problems containing more than :res-cls-cutoff1 and less than :res-cls-cutoff2.");
|
|
r.insert(":res-lit-cutoff-range3", CPK_UINT, "(default: 300) second cutoff (total number of literals) for Boolean variable elimination, for problems containing more than :res-cls-cutoff2.");
|
|
|
|
r.insert(":res-cls-cutoff1", CPK_UINT, "(default: 100000000) limit1 - total number of problems clauses for the second cutoff of Boolean variable elimination.");
|
|
r.insert(":res-cls-cutoff2", CPK_UINT, "(default: 700000000) limit2 - total number of problems clauses for the second cutoff of Boolean variable elimination.");
|
|
|
|
r.insert(":subsumption", CPK_BOOL, "(default: true) eliminate subsumed clauses.");
|
|
r.insert(":subsumption-limit", CPK_UINT, "(default: 100000000) approx. maximum number of literals visited during subsumption (and subsumption resolution).");
|
|
}
|
|
|
|
void simplifier::collect_statistics(statistics & st) {
|
|
st.update("subsumed", m_num_subsumed);
|
|
st.update("subsumption resolution", m_num_sub_res);
|
|
st.update("elim literals", m_num_elim_lits);
|
|
st.update("elim bool vars", m_num_elim_vars);
|
|
st.update("elim blocked clauses", m_num_blocked_clauses);
|
|
}
|
|
|
|
void simplifier::reset_statistics() {
|
|
m_num_blocked_clauses = 0;
|
|
m_num_subsumed = 0;
|
|
m_num_sub_res = 0;
|
|
m_num_elim_lits = 0;
|
|
m_num_elim_vars = 0;
|
|
}
|
|
};
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