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https://github.com/Z3Prover/z3
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fixplex
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
60dbfed69e
commit
6ac7c2b942
3 changed files with 105 additions and 122 deletions
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@ -99,19 +99,19 @@ namespace polysat {
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m_deps.pop_scope(n);
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while (n > 0) {
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switch (m_trail.back()) {
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case trail_i::inc_level_i:
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case trail_i::inc_level_i:
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--n;
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break;
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case trail_i::set_bound_i:
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case trail_i::set_bound_i:
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restore_bound();
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break;
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case trail_i::add_row_i:
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break;
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case trail_i::add_row_i:
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del_row(m_row_trail.back());
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m_row_trail.pop_back();
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break;
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case trail_i::add_ineq_i:
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break;
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case trail_i::add_ineq_i:
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restore_ineq();
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break;
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break;
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case trail_i::set_inconsistent_i:
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SASSERT(m_inconsistent);
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m_inconsistent = false;
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@ -147,45 +147,48 @@ namespace polysat {
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template<typename Ext>
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lbool fixplex<Ext>::make_feasible() {
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if (m_inconsistent)
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return l_false;
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++m_stats.m_num_checks;
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m_left_basis.reset();
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m_last_pivot_var = null_var;
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unsigned num_iterations = 0;
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unsigned num_repeated = 0;
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var_t v = null_var;
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m_num_repeated = 0;
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m_bland = false;
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unsigned num_iterations = 0;
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SASSERT(well_formed());
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while ((v = select_var_to_fix()) != null_var) {
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TRACE("polysat", display(tout << "v" << v << "\n"););
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if (!m_limit.inc() || num_iterations > m_max_iterations)
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return l_undef;
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check_blands_rule(v, num_repeated);
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switch (make_var_feasible(v)) {
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case l_true:
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++num_iterations;
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break;
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case l_false:
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m_to_patch.insert(v);
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set_infeasible_base(v);
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++m_stats.m_num_infeasible;
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while (m_limit.inc() && num_iterations < m_max_iterations) {
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if (inconsistent())
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return l_false;
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case l_undef:
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m_to_patch.insert(v);
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if (ineqs_are_violated())
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return l_false;
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if (!propagate())
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return l_false;
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if (is_satisfied())
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return l_true;
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if (!patch())
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return l_undef;
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}
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++num_iterations;
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SASSERT(well_formed());
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}
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SASSERT(well_formed());
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if (ineqs_are_violated())
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return l_false;
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if (ineqs_are_satisfied() && m_num_non_integral == 0)
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return l_true;
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return l_undef;
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}
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template<typename Ext>
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bool fixplex<Ext>::patch() {
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var_t v = select_var_to_fix();
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if (v == null_var)
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return false;
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check_blands_rule(v);
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switch (make_var_feasible(v)) {
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case l_true:
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return true;
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case l_false:
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m_to_patch.insert(v);
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set_infeasible_base(v);
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return true;
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case l_undef:
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m_to_patch.insert(v);
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return false;
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}
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UNREACHABLE();
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return true;
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}
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template<typename Ext>
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void fixplex<Ext>::add_row(var_t base_var, unsigned num_vars, var_t const* vars, rational const* coeffs) {
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vector<numeral> _coeffs;
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@ -277,6 +280,7 @@ namespace polysat {
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m_vars[var].m_is_base = false;
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m_vars[var].set_free();
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m_rows[r.id()].m_base = null_var;
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m_non_integral.remove(r.id());
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M.del(r);
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SASSERT(M.col_begin(var) == M.col_end(var));
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SASSERT(well_formed());
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@ -414,8 +418,6 @@ namespace polysat {
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numeral const& b = r.coeff();
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if (x == y)
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continue;
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if (y == m_last_pivot_var)
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continue;
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if (!has_minimal_trailing_zeros(y, b))
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continue;
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numeral new_y_value = solve_for(row_value - b * value(y), b);
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@ -478,7 +480,7 @@ namespace polysat {
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row r = base2row(x);
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for (auto const& c : M.col_entries(r)) {
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var_t y = c.var();
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if (x == y || y >= result || y == m_last_pivot_var)
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if (x == y || y >= result)
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continue;
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numeral const& b = c.coeff();
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if (can_improve(y, b)) {
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@ -615,7 +617,8 @@ namespace polysat {
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m_var2ineqs.reserve(std::max(v, w) + 1);
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m_var2ineqs[v].push_back(idx);
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m_var2ineqs[w].push_back(idx);
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m_ineqs_to_check.push_back(idx);
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touch_var(v);
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m_ineqs_to_propagate.insert(idx);
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m_trail.push_back(trail_i::add_ineq_i);
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m_ineqs.push_back(ineq(v, w, mk_leaf(dep), strict));
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}
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@ -630,49 +633,32 @@ namespace polysat {
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template<typename Ext>
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void fixplex<Ext>::touch_var(var_t v) {
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if (v >= m_var2ineqs.size())
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return;
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if (m_var_is_touched.get(v, false))
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return;
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m_var_is_touched.setx(v, true, false);
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for (auto idx : m_var2ineqs[v]) {
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if (!m_ineqs[idx].is_active) {
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m_ineqs[idx].is_active = true;
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m_ineqs_to_check.push_back(idx);
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}
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}
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}
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template<typename Ext>
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void fixplex<Ext>::reset_ineqs_to_check() {
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for (auto idx : m_ineqs_to_check) {
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if (idx >= m_ineqs.size())
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continue;
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auto& ineq = m_ineqs[idx];
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m_var_is_touched.setx(ineq.v, false, false);
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m_var_is_touched.setx(ineq.w, false, false);
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ineq.is_active = false;
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}
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m_ineqs_to_check.reset();
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m_touched_vars.insert(v);
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}
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/**
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* Check if the current assignment satisfies the inequalities
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*/
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template<typename Ext>
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bool fixplex<Ext>::ineqs_are_satisfied() {
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for (auto idx : m_ineqs_to_check) {
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if (idx >= m_ineqs.size())
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continue;
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auto& ineq = m_ineqs[idx];
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var_t v = ineq.v;
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var_t w = ineq.w;
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if (ineq.strict && value(v) >= value(w))
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return false;
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if (!ineq.strict && value(v) > value(w))
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return false;
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bool fixplex<Ext>::is_satisfied() {
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if (!m_to_patch.empty())
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return false;
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if (!m_non_integral.empty())
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return false;
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for (auto var : m_touched_vars) {
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for (auto idx : m_var2ineqs[var]) {
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if (idx >= m_ineqs.size())
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continue;
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auto& ineq = m_ineqs[idx];
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var_t v = ineq.v;
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var_t w = ineq.w;
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if (ineq.strict && value(v) >= value(w))
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return false;
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if (!ineq.strict && value(v) > value(w))
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return false;
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}
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}
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reset_ineqs_to_check();
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m_touched_vars.reset();
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return true;
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}
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@ -680,16 +666,16 @@ namespace polysat {
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* Propagate bounds and check if the current inequalities are satisfied
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*/
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template<typename Ext>
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bool fixplex<Ext>::ineqs_are_violated() {
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bool fixplex<Ext>::propagate() {
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lbool r;
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for (unsigned i = 0; i < m_ineqs_to_check.size(); ++i) {
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unsigned idx = m_ineqs_to_check[i];
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for (unsigned idx : m_ineqs_to_propagate) {
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if (idx >= m_ineqs.size())
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continue;
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if (r = propagate_ineqs(m_ineqs[idx]), r == l_false)
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return true;
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return false;
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}
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return false;
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m_ineqs_to_propagate.reset();
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return true;
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}
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/**
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@ -799,7 +785,7 @@ namespace polysat {
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z = base(r)
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d = base_coeff(r)
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b1 = (b >> tz(b))
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c1 = (c >> (tz(c) - tz(b)))
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c1 = (c >> tz(b))
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r <- b1 * r - c1 * r_x
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value(r) := b1 * value(r) - b1 * old_value(y) - c1 * value(r_x)
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value(z) := - value(r) / d
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@ -808,7 +794,6 @@ namespace polysat {
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template<typename Ext>
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void fixplex<Ext>::pivot(var_t x, var_t y, numeral const& b, numeral const& new_value) {
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++m_stats.m_num_pivots;
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m_last_pivot_var = x;
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SASSERT(is_base(x));
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SASSERT(!is_base(y));
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var_info& xI = m_vars[x];
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@ -909,7 +894,7 @@ namespace polysat {
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m_inconsistent = true;
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m_trail.push_back(trail_i::set_inconsistent_i);
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m_deps.linearize(todo, m_unsat_core);
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++m_stats.m_num_infeasible;
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}
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/**
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@ -975,15 +960,15 @@ namespace polysat {
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}
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template<typename Ext>
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void fixplex<Ext>::check_blands_rule(var_t v, unsigned& num_repeated) {
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void fixplex<Ext>::check_blands_rule(var_t v) {
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if (m_bland)
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return;
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if (!m_left_basis.contains(v))
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m_left_basis.insert(v);
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else {
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++num_repeated;
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m_bland = num_repeated > m_blands_rule_threshold;
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CTRACE("polysat", m_bland, tout << "using blands rule, " << num_repeated << "\n";);
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++m_num_repeated;
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m_bland = m_num_repeated > m_blands_rule_threshold;
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CTRACE("polysat", m_bland, tout << "using blands rule, " << m_num_repeated << "\n";);
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}
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}
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@ -1038,12 +1023,11 @@ namespace polysat {
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row r = base2row(x);
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m_vars[x].m_value = solve_for(row2value(r), row2base_coeff(r));
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touch_var(x);
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bool was_integral = row_is_integral(r);
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m_rows[r.id()].m_integral = is_solved(r);
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if (was_integral && !row_is_integral(r))
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++m_num_non_integral;
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else if (!was_integral && row_is_integral(r))
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--m_num_non_integral;
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if (row_is_integral(r))
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m_non_integral.remove(r.id());
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else
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m_non_integral.insert(r.id());
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}
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/**
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@ -1152,6 +1136,7 @@ namespace polysat {
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m_var_eqs.push_back(var_eq(x, y, r1, r2));
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}
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#if 0
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template<typename Ext>
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lbool fixplex<Ext>::propagate_bounds() {
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lbool r = l_true;
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@ -1163,6 +1148,7 @@ namespace polysat {
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return r;
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return l_true;
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}
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#endif
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//
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// DFS search propagating inequalities
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@ -1185,12 +1171,9 @@ namespace polysat {
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// std::cout << "propagate " << i0 << "\n";
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if (!propagate_ineq(i0))
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return l_false;
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if (old_lo == m_vars[i0.w].lo && i0.is_touched)
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return l_true;
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on_stack.reset();
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stack.reset();
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stack.push_back(std::make_pair(0, i0));
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i0.is_touched = true;
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on_stack.insert(i0.v);
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while (!stack.empty()) {
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if (!m_limit.inc())
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@ -1209,8 +1192,7 @@ namespace polysat {
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return l_false;
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bool is_onstack = on_stack.contains(i_out.w);
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if ((old_lo != m_vars[i_out.w].lo || !i_out.is_touched) && !is_onstack) {
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i_out.is_touched = true;
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if ((old_lo != m_vars[i_out.w].lo) && !is_onstack) {
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on_stack.insert(i_out.w);
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stack.back().first = ineq_out + 1;
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stack.push_back(std::make_pair(0, i_out));
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@ -1528,6 +1510,7 @@ namespace polysat {
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m_deps.linearize(a, m_unsat_core);
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SASSERT(!m_inconsistent);
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m_inconsistent = true;
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++m_stats.m_num_infeasible;
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m_trail.push_back(trail_i::set_inconsistent_i);
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TRACE("polysat", tout << "core: " << m_unsat_core << "\n";);
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}
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@ -1657,7 +1640,7 @@ return d;
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st.update("fixplex num pivots", m_stats.m_num_pivots);
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st.update("fixplex num infeasible", m_stats.m_num_infeasible);
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st.update("fixplex num checks", m_stats.m_num_checks);
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st.update("fixplex num non-integral", m_num_non_integral);
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st.update("fixplex num non-integral", m_non_integral.num_elems());
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st.update("fixplex num approximated row additions", m_stats.m_num_approx);
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}
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}
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