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https://github.com/Z3Prover/z3
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test 1
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
82a364ed7b
commit
20277f4a3f
5 changed files with 250 additions and 72 deletions
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@ -46,8 +46,6 @@ namespace polysat {
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m_rows.reset();
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m_left_basis.reset();
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m_base_vars.reset();
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// pivot(0,1, 2);
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}
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template<typename Ext>
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@ -61,10 +59,9 @@ namespace polysat {
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m_bland = false;
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SASSERT(well_formed());
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while ((v = select_var_to_fix()) != null_var) {
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TRACE("simplex", display(tout << "v" << v << "\n"););
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if (!m_limit.inc() || num_iterations > m_max_iterations) {
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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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}
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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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@ -87,6 +84,9 @@ namespace polysat {
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template<typename Ext>
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typename fixplex<Ext>::row
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fixplex<Ext>::add_row(var_t base_var, unsigned num_vars, var_t const* vars, numeral const* coeffs) {
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for (unsigned i = 0; i < num_vars; ++i)
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ensure_var(vars[i]);
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m_base_vars.reset();
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row r = M.mk_row();
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for (unsigned i = 0; i < num_vars; ++i)
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@ -179,11 +179,6 @@ namespace polysat {
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}
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template<typename Ext>
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bool fixplex<Ext>::in_bounds(var_t v) const {
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return in_bounds(value(v), lo(v), hi(v));
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}
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template<typename Ext>
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bool fixplex<Ext>::in_bounds(numeral const& val, numeral const& lo, numeral const& hi) const {
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if (lo == hi)
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@ -193,7 +188,6 @@ namespace polysat {
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return val < hi || lo <= val;
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}
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/**
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* Attempt to improve assigment to make x feasible.
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*
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@ -254,7 +248,7 @@ namespace polysat {
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int best_so_far = INT_MAX;
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numeral row_value = m_rows[r.id()].m_value;
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numeral a = m_rows[r.id()].m_base_coeff;
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numeral delta_y;
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numeral delta_y = 0;
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numeral delta_best = 0;
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bool best_in_bounds = false;
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@ -288,7 +282,7 @@ namespace polysat {
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is_improvement = true;
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else if (best_in_bounds && _in_bounds && num == best_so_far && col_sz < best_col_sz)
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is_improvement = true;
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else if (best_in_bounds && delta_y == delta_best && best_so_far == num && col_sz == best_col_sz)
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else if (best_in_bounds && !_in_bounds && delta_y == delta_best && best_so_far == num && col_sz == best_col_sz)
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is_plateau = true;
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if (is_improvement) {
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@ -310,6 +304,20 @@ namespace polysat {
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return result < max ? result : null_var;
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}
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template<typename Ext>
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void fixplex<Ext>::set_bounds(var_t v, numeral const& lo, numeral const& hi) {
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m_vars[v].m_lo = lo;
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m_vars[v].m_hi = hi;
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if (in_bounds(v))
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return;
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if (is_base(v))
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add_patch(v);
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else {
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NOT_IMPLEMENTED_YET();
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}
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}
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template<typename Ext>
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bool fixplex<Ext>::has_minimal_trailing_zeros(var_t y, numeral const& b) {
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unsigned tz1 = trailing_zeros(b);
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@ -426,6 +434,169 @@ namespace polysat {
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SASSERT(well_formed());
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}
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template<typename Ext>
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bool fixplex<Ext>::is_feasible() const {
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for (unsigned i = m_vars.size(); i-- > 0; )
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if (!in_bounds(i))
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return false;
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return true;
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}
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template<typename Ext>
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typename fixplex<Ext>::row
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fixplex<Ext>::get_infeasible_row() {
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SASSERT(is_base(m_infeasible_var));
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unsigned row_id = m_vars[m_infeasible_var].m_base2row;
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return row(row_id);
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}
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/**
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\brief Return the number of base variables that are non free and are v dependent.
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The function adds 1 to the result if v is non free.
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The function returns with a partial result r if r > best_so_far.
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This function is used to select the pivot variable.
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*/
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template<typename Ext>
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int fixplex<Ext>::get_num_non_free_dep_vars(var_t x_j, int best_so_far) {
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int result = is_non_free(x_j);
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for (auto const& col : M.col_entries(x_j)) {
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var_t s = m_rows[col.get_row().id()].m_base;
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result += is_non_free(s);
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if (result > best_so_far)
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return result;
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}
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return result;
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}
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template<typename Ext>
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void fixplex<Ext>::add_patch(var_t v) {
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SASSERT(is_base(v));
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CTRACE("polysat", !in_bounds(v), tout << "Add patch: v" << v << "\n";);
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if (!in_bounds(v))
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m_to_patch.insert(v);
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}
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template<typename Ext>
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var_t fixplex<Ext>::select_var_to_fix() {
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switch (pivot_strategy()) {
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case S_BLAND:
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return select_smallest_var();
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case S_GREATEST_ERROR:
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return select_error_var(false);
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case S_LEAST_ERROR:
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return select_error_var(true);
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default:
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return select_smallest_var();
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}
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}
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template<typename Ext>
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var_t fixplex<Ext>::select_error_var(bool least) {
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var_t best = null_var;
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numeral best_error = 0, curr_error = 0;
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for (var_t v : m_to_patch) {
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if (in_bounds(v))
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continue;
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if (lo(v) - value(v) < value(v) - hi(v))
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curr_error = lo(v) - value(v);
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else
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curr_error = value(v) - hi(v) - 1;
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if ((best == null_var) ||
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(least && curr_error < best_error) ||
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(!least && curr_error > best_error)) {
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best = v;
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best_error = curr_error;
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}
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}
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if (best == null_var)
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m_to_patch.clear(); // all variables are satisfied
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else
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m_to_patch.erase(best);
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return best;
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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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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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}
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}
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template<typename Ext>
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std::ostream& fixplex<Ext>::display(std::ostream& out) const {
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M.display(out);
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for (unsigned i = 0; i < m_vars.size(); ++i) {
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var_info const& vi = m_vars[i];
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out << "v" << i << " " << value(i) << " [" << lo(i) << ", " << hi(i) << "[ ";
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if (vi.m_is_base) out << "b:" << vi.m_base2row << " ";
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out << "\n";
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}
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return out;
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}
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template<typename Ext>
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void fixplex<Ext>::display_row(std::ostream& out, row const& r, bool values) {
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for (auto const& e : M.row_entries(r)) {
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var_t v = e.m_var;
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if (e.m_coeff != 1)
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out << e.m_coeff << " * ";
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out << "v" << v << " ";
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if (values)
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out << value(v) << " [" << lo(v) << ", " << hi(v) << "[ ";
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}
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return out << "\n";
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}
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template<typename Ext>
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bool fixplex<Ext>::well_formed() const {
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SASSERT(M.well_formed());
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for (unsigned i = 0; i < m_rows.size(); ++i) {
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var_t s = m_rows[i].m_base;
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if (s == null_var)
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continue;
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SASSERT(i == m_vars[s].m_base2row);
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VERIFY(well_formed_row(row(i)));
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}
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for (unsigned i = 0; i < m_vars.size(); ++i) {
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SASSERT(is_base(i) || in_bounds(i));
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}
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return true;
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}
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template<typename Ext>
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bool fixplex<Ext>::well_formed_row(row const& r) const {
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var_t s = m_rows[r.id()].m_base;
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(void)s;
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SASSERT(m_vars[s].m_base2row == r.id());
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SASSERT(m_vars[s].m_is_base);
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numeral sum = 0;
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for (auto const& e : M.row_entries(r)) {
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sum += value(e.m_var) * e.m_coeff;
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SASSERT(s != e.m_var || m_rows[r.id()].m_base_coeff == e.m_coeff);
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}
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if (sum != 0) {
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IF_VERBOSE(0, M.display_row(verbose_stream(), r););
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TRACE("polysat", display(tout << "non-well formed row\n"); M.display_row(tout << "row: ", r););
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throw default_exception("non-well formed row");
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}
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return true;
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}
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template<typename Ext>
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void fixplex<Ext>::collect_statistics(::statistics & st) const {
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M.collect_statistics(st);
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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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}
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}
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