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https://github.com/Z3Prover/z3
synced 2025-04-07 18:05:21 +00:00
na
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
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2512a958b9
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@ -31,7 +31,7 @@ class create_cut {
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explanation* m_ex; // the conflict explanation
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unsigned m_inf_col; // a basis column which has to be an integer but has a non integral value
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const row_strip<mpq>& m_row;
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const int_solver& m_int_solver;
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const int_solver& lia;
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mpq m_lcm_den;
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mpq m_f;
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mpq m_one_minus_f;
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@ -42,18 +42,18 @@ class create_cut {
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#endif
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struct found_big {};
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const impq & get_value(unsigned j) const { return m_int_solver.get_value(j); }
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bool is_real(unsigned j) const { return m_int_solver.is_real(j); }
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bool at_lower(unsigned j) const { return m_int_solver.at_lower(j); }
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bool at_upper(unsigned j) const { return m_int_solver.at_upper(j); }
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const impq & lower_bound(unsigned j) const { return m_int_solver.lower_bound(j); }
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const impq & upper_bound(unsigned j) const { return m_int_solver.upper_bound(j); }
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constraint_index column_lower_bound_constraint(unsigned j) const { return m_int_solver.column_lower_bound_constraint(j); }
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constraint_index column_upper_bound_constraint(unsigned j) const { return m_int_solver.column_upper_bound_constraint(j); }
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bool column_is_fixed(unsigned j) const { return m_int_solver.lra.column_is_fixed(j); }
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const impq & get_value(unsigned j) const { return lia.get_value(j); }
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bool is_real(unsigned j) const { return lia.is_real(j); }
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bool at_lower(unsigned j) const { return lia.at_lower(j); }
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bool at_upper(unsigned j) const { return lia.at_upper(j); }
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const impq & lower_bound(unsigned j) const { return lia.lower_bound(j); }
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const impq & upper_bound(unsigned j) const { return lia.upper_bound(j); }
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constraint_index column_lower_bound_constraint(unsigned j) const { return lia.column_lower_bound_constraint(j); }
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constraint_index column_upper_bound_constraint(unsigned j) const { return lia.column_upper_bound_constraint(j); }
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bool column_is_fixed(unsigned j) const { return lia.lra.column_is_fixed(j); }
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void int_case_in_gomory_cut(unsigned j) {
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lp_assert(m_int_solver.column_is_int(j) && m_fj.is_pos());
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lp_assert(lia.column_is_int(j) && m_fj.is_pos());
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TRACE("gomory_cut_detail",
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tout << " k = " << m_k;
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tout << ", fj: " << m_fj << ", ";
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@ -131,7 +131,7 @@ class create_cut {
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if (pol.size() == 1) {
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TRACE("gomory_cut_detail", tout << "pol.size() is 1" << std::endl;);
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unsigned v = pol[0].second;
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lp_assert(m_int_solver.column_is_int(v));
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lp_assert(lia.column_is_int(v));
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const mpq& a = pol[0].first;
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m_k /= a;
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if (a.is_pos()) { // we have av >= k
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@ -153,7 +153,7 @@ class create_cut {
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// normalize coefficients of integer parameters to be integers.
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for (auto & pi: pol) {
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pi.first *= m_lcm_den;
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SASSERT(!m_int_solver.column_is_int(pi.second) || pi.first.is_int());
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SASSERT(!lia.column_is_int(pi.second) || pi.first.is_int());
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}
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m_k *= m_lcm_den;
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}
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@ -207,7 +207,7 @@ class create_cut {
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}
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void dump_declaration(std::ostream& out, unsigned v) const {
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out << "(declare-const " << var_name(v) << (m_int_solver.column_is_int(v) ? " Int" : " Real") << ")\n";
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out << "(declare-const " << var_name(v) << (lia.column_is_int(v) ? " Int" : " Real") << ")\n";
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}
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void dump_declarations(std::ostream& out) const {
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@ -217,7 +217,7 @@ class create_cut {
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}
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for (const auto& p : m_t) {
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unsigned v = p.var();
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if (m_int_solver.lra.is_term(v)) {
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if (lia.lra.is_term(v)) {
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dump_declaration(out, v);
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}
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}
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@ -276,7 +276,7 @@ public:
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void dump(std::ostream& out) {
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out << "applying cut at:\n"; print_linear_combination_indices_only<row_strip<mpq>, mpq>(m_row, out); out << std::endl;
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for (auto & p : m_row) {
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m_int_solver.lra.m_mpq_lar_core_solver.m_r_solver.print_column_info(p.var(), out);
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lia.lra.m_mpq_lar_core_solver.m_r_solver.print_column_info(p.var(), out);
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}
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out << "inf_col = " << m_inf_col << std::endl;
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}
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@ -334,20 +334,20 @@ public:
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return report_conflict_from_gomory_cut();
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if (some_int_columns)
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adjust_term_and_k_for_some_ints_case_gomory();
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lp_assert(m_int_solver.current_solution_is_inf_on_cut());
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lp_assert(lia.current_solution_is_inf_on_cut());
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TRACE("gomory_cut_detail", dump_cut_and_constraints_as_smt_lemma(tout););
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m_int_solver.lra.subs_term_columns(m_t);
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lia.lra.subs_term_columns(m_t);
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TRACE("gomory_cut", print_linear_combination_of_column_indices_only(m_t.coeffs_as_vector(), tout << "gomory cut:"); tout << " <= " << m_k << std::endl;);
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return lia_move::cut;
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}
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create_cut(lar_term & t, mpq & k, explanation* ex, unsigned basic_inf_int_j, const row_strip<mpq>& row, const int_solver& int_slv ) :
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create_cut(lar_term & t, mpq & k, explanation* ex, unsigned basic_inf_int_j, const row_strip<mpq>& row, const int_solver& lia) :
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m_t(t),
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m_k(k),
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m_ex(ex),
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m_inf_col(basic_inf_int_j),
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m_row(row),
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m_int_solver(int_slv),
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lia(lia),
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m_lcm_den(1),
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m_f(fractional_part(get_value(basic_inf_int_j).x)),
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m_one_minus_f(1 - m_f) {}
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@ -359,7 +359,6 @@ lia_move gomory::cut(lar_term & t, mpq & k, explanation* ex, unsigned basic_inf_
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return cc.cut();
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}
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bool gomory::is_gomory_cut_target(const row_strip<mpq>& row) {
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// All non base variables must be at their bounds and assigned to rationals (that is, infinitesimals are not allowed).
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unsigned j;
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@ -158,7 +158,7 @@ namespace lp {
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// u += ncoeff * lower_bound(j).get_rational();
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u.addmul(ncoeff, lra.column_lower_bound(j).x);
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}
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lia.add_to_explanation_from_fixed_or_boxed_column(j);
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add_to_explanation_from_fixed_or_boxed_column(j);
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}
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else if (gcds.is_zero()) {
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gcds = abs_ncoeff;
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@ -186,7 +186,15 @@ namespace lp {
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void int_gcd_test::fill_explanation_from_fixed_columns(const row_strip<mpq> & row) {
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for (const auto & c : row) {
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if (lra.column_is_fixed(c.var()))
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lia.add_to_explanation_from_fixed_or_boxed_column(c.var());
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add_to_explanation_from_fixed_or_boxed_column(c.var());
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}
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}
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void int_gcd_test::add_to_explanation_from_fixed_or_boxed_column(unsigned j) {
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constraint_index lc, uc;
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lra.get_bound_constraint_witnesses_for_column(j, lc, uc);
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lia.m_ex->push_justification(lc);
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lia.m_ex->push_justification(uc);
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}
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}
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@ -9,6 +9,15 @@ Abstract:
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Gcd_Test heuristic
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gcd test
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5*x + 3*y + 6*z = 5
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suppose x is fixed at 2.
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so we have 10 + 3(y + 2z) = 5
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5 = -3(y + 2z)
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this is unsolvable because 5/3 is not an integer.
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so we create a lemma that rules out this condition.
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Author:
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Nikolaj Bjorner (nbjorner)
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Lev Nachmanson (levnach)
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@ -33,7 +42,7 @@ namespace lp {
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mpq const & lcm_den,
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mpq const & consts);
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void fill_explanation_from_fixed_columns(const row_strip<mpq> & row);
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void add_to_explanation_from_fixed_or_boxed_column(unsigned j);
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public:
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int_gcd_test(int_solver& lia);
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~int_gcd_test() {}
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@ -312,12 +312,6 @@ lia_move int_solver::patch_nbasic_columns() {
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}
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// TBD: move to gcd-test
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void int_solver::add_to_explanation_from_fixed_or_boxed_column(unsigned j) {
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constraint_index lc, uc;
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lra.get_bound_constraint_witnesses_for_column(j, lc, uc);
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m_ex->push_justification(lc);
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m_ex->push_justification(uc);
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}
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int_solver::int_solver(lar_solver& lar_slv) :
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@ -52,6 +52,7 @@ public:
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// methods
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int_solver(lar_solver& lp);
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// main function to check that the solution provided by lar_solver is valid for integral values,
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// or provide a way of how it can be adjusted.
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lia_move check(explanation *);
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bool at_upper(unsigned j) const;
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private:
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// how to tighten bounds for integer variables.
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bool gcd_test_for_row(static_matrix<mpq, numeric_pair<mpq>> & A, unsigned i);
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// gcd test
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// 5*x + 3*y + 6*z = 5
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// suppose x is fixed at 2.
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// so we have 10 + 3(y + 2z) = 5
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// 5 = -3(y + 2z)
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// this is unsolvable because 5/3 is not an integer.
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// so we create a lemma that rules out this condition.
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//
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bool gcd_test(); // returns false in case of failure. Creates a theory lemma in case of failure.
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bool branch(const lp_constraint<mpq, mpq> & new_inequality);
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bool ext_gcd_test(const row_strip<mpq>& row,
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mpq const & least_coeff,
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mpq const & lcm_den,
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mpq const & consts);
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void fill_explanation_from_fixed_columns(const row_strip<mpq> & row);
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void add_to_explanation_from_fixed_or_boxed_column(unsigned j);
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lia_move patch_nbasic_columns();
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bool get_freedom_interval_for_column(unsigned j, bool & inf_l, impq & l, bool & inf_u, impq & u, mpq & m);
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private:
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bool is_boxed(unsigned j) const;
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bool is_fixed(unsigned j) const;
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bool is_free(unsigned j) const;
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