From 066b5334ad5882dff635abd354928f14b9a3c4d2 Mon Sep 17 00:00:00 2001 From: Lev Nachmanson Date: Sat, 22 Sep 2018 20:57:59 -0700 Subject: [PATCH] refactor some parameters into fields in Gomory cuts Signed-off-by: Lev Nachmanson --- src/util/lp/gomory.cpp | 119 +++++++++++++++++++++-------------------- 1 file changed, 62 insertions(+), 57 deletions(-) diff --git a/src/util/lp/gomory.cpp b/src/util/lp/gomory.cpp index 96b3ab395..ad1c02625 100644 --- a/src/util/lp/gomory.cpp +++ b/src/util/lp/gomory.cpp @@ -27,11 +27,15 @@ class gomory::imp { lar_term & m_t; // the term to return in the cut mpq & m_k; // the right side of the cut explanation& m_ex; // the conflict explanation - unsigned m_inf_col; // a basis column which has to be an integer but has a not integral value + unsigned m_inf_col; // a basis column which has to be an integer but has a non integral value const row_strip& m_row; - const int_solver& m_int_solver; - - + const int_solver& m_int_solver; + mpq m_lcm_den; + mpq m_f; + mpq m_one_minus_f; + mpq m_fj; + mpq m_one_minus_fj; + const impq & get_value(unsigned j) const { return m_int_solver.get_value(j); } bool is_real(unsigned j) const { return m_int_solver.is_real(j); } bool at_lower(unsigned j) const { return m_int_solver.at_lower(j); } @@ -42,66 +46,60 @@ class gomory::imp { constraint_index column_upper_bound_constraint(unsigned j) const { return m_int_solver.column_upper_bound_constraint(j); } bool column_is_fixed(unsigned j) const { return m_int_solver.m_lar_solver->column_is_fixed(j); } - void int_case_in_gomory_cut(const mpq & a, unsigned j, - mpq & lcm_den, const mpq& f0, const mpq& one_minus_f0) { - lp_assert(is_int(j) && !a.is_int()); - mpq fj = fractional_part(a); + void int_case_in_gomory_cut(unsigned j) { + lp_assert(is_int(j) && m_fj.is_pos()); TRACE("gomory_cut_detail", - tout << a << " j=" << j << " k = " << m_k; - tout << ", fj: " << fj << ", "; - tout << "a - fj = " << a - fj << ", "; + tout << " k = " << m_k; + tout << ", fj: " << m_fj << ", "; tout << (at_lower(j)?"at_lower":"at_upper")<< std::endl; ); - lp_assert(fj.is_pos() && (a - fj).is_int()); mpq new_a; if (at_lower(j)) { - new_a = fj <= one_minus_f0 ? fj / one_minus_f0 : ((1 - fj) / f0); + new_a = m_fj <= m_one_minus_f ? m_fj / m_one_minus_f : ((1 - m_fj) / m_f); lp_assert(new_a.is_pos()); m_k.addmul(new_a, lower_bound(j).x); - m_ex.push_justification(column_lower_bound_constraint(j), new_a); + m_ex.push_justification(column_lower_bound_constraint(j)); } else { lp_assert(at_upper(j)); // the upper terms are inverted: therefore we have the minus - new_a = - (fj <= f0 ? fj / f0 : ((1 - fj) / one_minus_f0)); + new_a = - (m_fj <= m_f ? m_fj / m_f : ((1 - m_fj) / m_one_minus_f)); lp_assert(new_a.is_neg()); m_k.addmul(new_a, upper_bound(j).x); - m_ex.push_justification(column_upper_bound_constraint(j), new_a); + m_ex.push_justification(column_upper_bound_constraint(j)); } m_t.add_monomial(new_a, j); - lcm_den = lcm(lcm_den, denominator(new_a)); - TRACE("gomory_cut_detail", tout << "v" << j << " new_a = " << new_a << ", k = " << m_k << ", lcm_den = " << lcm_den << "\n";); + m_lcm_den = lcm(m_lcm_den, denominator(new_a)); + TRACE("gomory_cut_detail", tout << "v" << j << " new_a = " << new_a << ", k = " << m_k << ", m_lcm_den = " << m_lcm_den << "\n";); } - void real_case_in_gomory_cut(const mpq & a, unsigned x_j, const mpq& f0, const mpq& one_minus_f0) { + void real_case_in_gomory_cut(const mpq & a, unsigned j) { TRACE("gomory_cut_detail_real", tout << "real\n";); mpq new_a; - if (at_lower(x_j)) { + if (at_lower(j)) { if (a.is_pos()) { - new_a = a / one_minus_f0; + new_a = a / m_one_minus_f; } else { - new_a = a / f0; - new_a.neg(); + new_a = - a / m_f; } - m_k.addmul(new_a, lower_bound(x_j).x); // is it a faster operation than - // k += lower_bound(x_j).x * new_a; - m_ex.push_justification(column_lower_bound_constraint(x_j), new_a); + m_k.addmul(new_a, lower_bound(j).x); // is it a faster operation than + // k += lower_bound(j).x * new_a; + m_ex.push_justification(column_lower_bound_constraint(j)); } else { - lp_assert(at_upper(x_j)); + lp_assert(at_upper(j)); if (a.is_pos()) { - new_a = a / f0; - new_a.neg(); // the upper terms are inverted. + new_a = - a / m_f; } else { - new_a = a / one_minus_f0; + new_a = a / m_one_minus_f; } - m_k.addmul(new_a, upper_bound(x_j).x); // k += upper_bound(x_j).x * new_a; - m_ex.push_justification(column_upper_bound_constraint(x_j), new_a); + m_k.addmul(new_a, upper_bound(j).x); // k += upper_bound(j).x * new_a; + m_ex.push_justification(column_upper_bound_constraint(j)); } - TRACE("gomory_cut_detail_real", tout << a << "*v" << x_j << " k: " << m_k << "\n";); - m_t.add_monomial(new_a, x_j); + TRACE("gomory_cut_detail_real", tout << a << "*v" << j << " k: " << m_k << "\n";); + m_t.add_monomial(new_a, j); } lia_move report_conflict_from_gomory_cut() { @@ -111,7 +109,7 @@ class gomory::imp { return lia_move::conflict; } - void adjust_term_and_k_for_some_ints_case_gomory(mpq &lcm_den) { + void adjust_term_and_k_for_some_ints_case_gomory() { lp_assert(!m_t.is_empty()); // k = 1 + sum of m_t at bounds auto pol = m_t.coeffs_as_vector(); @@ -134,16 +132,16 @@ class gomory::imp { m_t.add_monomial(mpq(1), v); } } else { - lcm_den = lcm(lcm_den, denominator(m_k)); - lp_assert(lcm_den.is_pos()); - TRACE("gomory_cut_detail", tout << "pol.size() > 1 den: " << lcm_den << std::endl;); - if (!lcm_den.is_one()) { + m_lcm_den = lcm(m_lcm_den, denominator(m_k)); + lp_assert(m_lcm_den.is_pos()); + TRACE("gomory_cut_detail", tout << "pol.size() > 1 den: " << m_lcm_den << std::endl;); + if (!m_lcm_den.is_one()) { // normalize coefficients of integer parameters to be integers. for (auto & pi: pol) { - pi.first *= lcm_den; + pi.first *= m_lcm_den; SASSERT(!is_int(pi.second) || pi.first.is_int()); } - m_k *= lcm_den; + m_k *= m_lcm_den; } // negate everything to return -pol <= -m_k for (const auto & pi: pol) { @@ -275,14 +273,14 @@ public: // gomory will be t <= k and the current solution has a property t > k m_k = 1; m_t.clear(); - mpq lcm_den(1); + mpq m_lcm_den(1); bool some_int_columns = false; - mpq f0 = fractional_part(get_value(m_inf_col)); - TRACE("gomory_cut_detail", tout << "f0: " << f0 << ", "; - tout << "1 - f0: " << 1 - f0 << ", get_value(m_inf_col).x - f0 = " << get_value(m_inf_col).x - f0;); - lp_assert(f0.is_pos() && (get_value(m_inf_col).x - f0).is_int()); + mpq m_f = fractional_part(get_value(m_inf_col)); + TRACE("gomory_cut_detail", tout << "m_f: " << m_f << ", "; + tout << "1 - m_f: " << 1 - m_f << ", get_value(m_inf_col).x - m_f = " << get_value(m_inf_col).x - m_f;); + lp_assert(m_f.is_pos() && (get_value(m_inf_col).x - m_f).is_int()); - mpq one_min_f0 = 1 - f0; + mpq one_min_m_f = 1 - m_f; for (const auto & p : m_row) { unsigned j = p.var(); if (j == m_inf_col) { @@ -290,20 +288,26 @@ public: TRACE("gomory_cut_detail", tout << "seeing basic var";); continue; } - // make the format compatible with the format used in: Integrating Simplex with DPLL(T) - mpq a = - p.coeff(); - if (is_real(j)) - real_case_in_gomory_cut(a, j, f0, one_min_f0); - else if (!a.is_int()) { // fj will be zero and no monomial will be added + + // use -p.coeff() to make the format compatible with the format used in: Integrating Simplex with DPLL(T) + if (is_real(j)) { + real_case_in_gomory_cut(- p.coeff(), j); + } else { + if (p.coeff().is_int()) { + // m_fj will be zero and no monomial will be added + continue; + } some_int_columns = true; - int_case_in_gomory_cut(a, j, lcm_den, f0, one_min_f0); + m_fj = fractional_part(-p.coeff()); + m_one_minus_fj = 1 - m_fj; + int_case_in_gomory_cut(j); } } if (m_t.is_empty()) return report_conflict_from_gomory_cut(); if (some_int_columns) - adjust_term_and_k_for_some_ints_case_gomory(lcm_den); + adjust_term_and_k_for_some_ints_case_gomory(); lp_assert(m_int_solver.current_solution_is_inf_on_cut()); TRACE("gomory_cut_detail", dump_cut_and_constraints_as_smt_lemma(tout);); m_int_solver.m_lar_solver->subs_term_columns(m_t); @@ -317,9 +321,10 @@ public: m_ex(ex), m_inf_col(basic_inf_int_j), m_row(row), - m_int_solver(int_slv) - { - } + m_int_solver(int_slv), + m_lcm_den(1), + m_f(fractional_part(get_value(basic_inf_int_j).x)), + m_one_minus_f(1 - m_f) {} };