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https://github.com/Z3Prover/z3
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add assertions to simplifier
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
bd879c1016
commit
e28701a64c
14 changed files with 391 additions and 213 deletions
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@ -905,28 +905,6 @@ namespace smt {
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r1.reset_var_pos(m_var_pos);
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}
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/**
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\brief Select tightest variable x_i to pivot with x_j. The goal
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is to select a x_i such that the value of x_j is increased
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(decreased) if inc = true (inc = false), and the tableau
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remains feasible. Store the gain in x_j of the pivoting
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operation in 'gain'. Note the gain can be too much. That is,
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it may make x_i infeasible. In this case, instead of pivoting
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we move x_j to its upper bound (lower bound) when inc = true (inc = false).
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If no x_i imposes a restriction on x_j, then return null_theory_var.
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That is, x_j is free to move to its upper bound (lower bound).
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Get the equations for x_j:
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x_i1 = coeff_1 * x_j + rest_1
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...
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x_in = coeff_n * x_j + rest_n
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gain_k := (upper_bound(x_ik) - value(x_ik))/coeff_k
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*/
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template<typename Ext>
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bool theory_arith<Ext>::is_safe_to_leave(theory_var x, bool inc, bool& has_int, bool& shared) {
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@ -958,6 +936,29 @@ namespace smt {
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return !was_unsafe || unbounded;
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}
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/**
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\brief Select tightest variable x_i to pivot with x_j. The goal
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is to select a x_i such that the value of x_j is increased
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(decreased) if inc = true (inc = false), and the tableau
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remains feasible. Store the gain in x_j of the pivoting
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operation in 'gain'. Note the gain can be too much. That is,
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it may make x_i infeasible. In this case, instead of pivoting
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we move x_j to its upper bound (lower bound) when inc = true (inc = false).
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If no x_i imposes a restriction on x_j, then return null_theory_var.
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That is, x_j is free to move to its upper bound (lower bound).
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Get the equations for x_j:
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x_i1 = coeff_1 * x_j + rest_1
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...
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x_in = coeff_n * x_j + rest_n
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gain_k := (upper_bound(x_ik) - value(x_ik))/coeff_k
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*/
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template<typename Ext>
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theory_var theory_arith<Ext>::pick_var_to_leave(
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bool has_int, theory_var x_j, bool inc,
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@ -1458,6 +1459,166 @@ namespace smt {
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return result;
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}
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#if 0
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/**
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\brief Maximize (Minimize) the given temporary row.
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Return true if succeeded.
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*/
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template<typename Ext>
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typename theory_arith<Ext>::max_min_t theory_arith<Ext>::max_min_new(row & r, bool max, bool& has_shared) {
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TRACE("max_min", tout << "max_min...\n";);
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m_stats.m_max_min++;
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bool skipped_row = false;
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has_shared = false;
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SASSERT(valid_row_assignment());
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SASSERT(satisfy_bounds());
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theory_var x_i = null_theory_var;
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theory_var x_j = null_theory_var;
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bool inc = false;
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numeral a_ij, curr_a_ij, coeff, curr_coeff;
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inf_numeral gain, curr_gain;
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#ifdef _TRACE
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unsigned i = 0;
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#endif
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max_min_t result = BEST_EFFORT;
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while (true) {
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x_j = null_theory_var;
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x_i = null_theory_var;
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gain.reset();
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TRACE("opt", tout << "i: " << i << ", max: " << max << "\n"; display_row(tout, r, true); tout << "state:\n"; display(tout); i++;);
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typename vector<row_entry>::const_iterator it = r.begin_entries();
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typename vector<row_entry>::const_iterator end = r.end_entries();
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for (; it != end; ++it) {
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if (it->is_dead()) continue;
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theory_var curr_x_j = it->m_var;
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SASSERT(is_non_base(curr_x_j));
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curr_coeff = it->m_coeff;
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bool curr_inc = curr_coeff.is_pos() ? max : !max;
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bool has_int = false;
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if ((curr_inc && at_upper(curr_x_j)) || (!curr_inc && at_lower(curr_x_j)))
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continue; // variable cannot be used for max/min.
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if (!is_safe_to_leave(curr_x_j, curr_inc, has_int, has_shared)) {
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skipped_row = true;
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continue;
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}
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theory_var curr_x_i = pick_var_to_leave(has_int, curr_x_j, curr_inc, curr_a_ij, curr_gain, skipped_row);
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if (curr_x_i == null_theory_var) {
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TRACE("opt", tout << "unbounded\n";);
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// we can increase/decrease curr_x_j as much as we want.
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x_i = null_theory_var; // unbounded
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x_j = curr_x_j;
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inc = curr_inc;
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break;
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}
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else if (curr_gain > gain) {
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x_i = curr_x_i;
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x_j = curr_x_j;
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a_ij = curr_a_ij;
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coeff = curr_coeff;
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gain = curr_gain;
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inc = curr_inc;
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}
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else if (curr_gain.is_zero() && (x_i == null_theory_var || curr_x_i < x_i)) {
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x_i = curr_x_i;
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x_j = curr_x_j;
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a_ij = curr_a_ij;
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coeff = curr_coeff;
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gain = curr_gain;
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inc = curr_inc;
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// continue
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}
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}
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TRACE("opt", tout << "after traversing row:\nx_i: v" << x_i << ", x_j: v" << x_j << ", gain: " << gain << "\n";
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tout << "skipped row: " << (skipped_row?"yes":"no") << "\n";
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display(tout););
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if (x_j == null_theory_var) {
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TRACE("opt", tout << "row is " << (max ? "maximized" : "minimized") << "\n";);
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SASSERT(valid_row_assignment());
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SASSERT(satisfy_bounds());
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result = skipped_row?BEST_EFFORT:OPTIMIZED;
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break;
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}
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if (x_i == null_theory_var) {
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// can increase/decrease x_j as much as we want.
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if (inc && upper(x_j) && !skipped_row) {
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update_value(x_j, upper_bound(x_j) - get_value(x_j));
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TRACE("opt", tout << "moved v" << x_j << " to upper bound\n";);
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SASSERT(valid_row_assignment());
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SASSERT(satisfy_bounds());
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SASSERT(satisfy_integrality());
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continue;
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}
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if (!inc && lower(x_j) && !skipped_row) {
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update_value(x_j, lower_bound(x_j) - get_value(x_j));
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TRACE("opt", tout << "moved v" << x_j << " to lower bound\n";);
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SASSERT(valid_row_assignment());
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SASSERT(satisfy_bounds());
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SASSERT(satisfy_integrality());
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continue;
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}
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result = skipped_row?BEST_EFFORT:UNBOUNDED;
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break;
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}
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if (!is_fixed(x_j) && is_bounded(x_j) && !skipped_row && (upper_bound(x_j) - lower_bound(x_j) <= gain)) {
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// can increase/decrease x_j up to upper/lower bound.
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if (inc) {
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update_value(x_j, upper_bound(x_j) - get_value(x_j));
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TRACE("opt", tout << "moved v" << x_j << " to upper bound\n";);
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}
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else {
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update_value(x_j, lower_bound(x_j) - get_value(x_j));
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TRACE("opt", tout << "moved v" << x_j << " to lower bound\n";);
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}
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SASSERT(valid_row_assignment());
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SASSERT(satisfy_bounds());
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SASSERT(satisfy_integrality());
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continue;
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}
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TRACE("opt", tout << "max: " << max << ", x_i: v" << x_i << ", x_j: v" << x_j << ", a_ij: " << a_ij << ", coeff: " << coeff << "\n";
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if (upper(x_i)) tout << "upper x_i: " << upper_bound(x_i) << " ";
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if (lower(x_i)) tout << "lower x_i: " << lower_bound(x_i) << " ";
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tout << "value x_i: " << get_value(x_i) << "\n";
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if (upper(x_j)) tout << "upper x_j: " << upper_bound(x_j) << " ";
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if (lower(x_j)) tout << "lower x_j: " << lower_bound(x_j) << " ";
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tout << "value x_j: " << get_value(x_j) << "\n";
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);
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pivot<true>(x_i, x_j, a_ij, false);
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SASSERT(is_non_base(x_i));
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SASSERT(is_base(x_j));
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bool move_xi_to_lower;
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if (inc)
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move_xi_to_lower = a_ij.is_pos();
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else
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move_xi_to_lower = a_ij.is_neg();
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if (!move_to_bound(x_i, move_xi_to_lower)) {
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result = BEST_EFFORT;
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break;
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}
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row & r2 = m_rows[get_var_row(x_j)];
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coeff.neg();
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add_tmp_row(r, coeff, r2);
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SASSERT(r.get_idx_of(x_j) == -1);
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SASSERT(valid_row_assignment());
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SASSERT(satisfy_bounds());
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SASSERT(satisfy_integrality());
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}
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TRACE("opt", display(tout););
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return result;
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}
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#endif
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/**
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Move the variable x_i maximally towards its bound as long as
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bounds of other variables are not violated.
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