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fix dump utility for cuts

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2018-09-19 14:32:56 -07:00
commit 3c553c17e8
9 changed files with 165 additions and 61 deletions
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145
src/util/lp/gomory.cpp
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@ -20,6 +20,7 @@
#include "util/lp/gomory.h"
#include "util/lp/int_solver.h"
#include "util/lp/lar_solver.h"
#include "util/lp/lp_utils.h"
namespace lp {
class gomory::imp {
@ -40,35 +41,38 @@ class gomory::imp {
constraint_index column_lower_bound_constraint(unsigned j) const { return m_int_solver.column_lower_bound_constraint(j); }
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) {
mpq & lcm_den, const mpq& f0, const mpq& one_minus_f0) {
lp_assert(is_int(j) && !a.is_int());
mpq fj = int_solver::fractional_part(a);
lp_assert(fj.is_pos());
mpq fj = fractional_part(a);
TRACE("gomory_cut_detail",
tout << a << " j=" << j << " k = " << m_k;
tout << ", fj: " << fj << ", ";
tout << "f0: " << f0 << ", ";
tout << "1 - f0: " << 1 - f0 << ", ";
tout << "a - fj = " << a - fj << ", ";
tout << (at_lower(j)?"at_lower":"at_upper")<< std::endl;
);
lp_assert(fj.is_pos() && (a - fj).is_int());
mpq new_a;
mpq one_minus_fj = 1 - fj;
if (at_lower(j)) {
new_a = fj < one_minus_f0? fj / one_minus_f0 : one_minus_fj / f0;
new_a = fj <= one_minus_f0 ? fj / one_minus_f0 : ((1 - fj) / f0);
m_k.addmul(new_a, lower_bound(j).x);
// m_k += (new_a * lower_bound(j).x);
lp_assert(new_a.is_pos());
m_ex.push_justification(column_lower_bound_constraint(j), new_a);
}
else {
lp_assert(at_upper(j));
// the upper terms are inverted: therefore we have the minus
new_a = - (fj < f0? fj / f0 : one_minus_fj / one_minus_f0);
new_a = - (fj <= f0 ? fj / f0 : ((1 - fj) / one_minus_f0));
lp_assert(new_a.is_neg());
m_k.addmul(new_a, upper_bound(j).x);
// m_k += (new_a * upper_bound(j).x);
m_ex.push_justification(column_upper_bound_constraint(j), new_a);
}
TRACE("gomory_cut_detail", tout << "new_a: " << new_a << " k: " << m_k << "\n";);
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";);
}
void real_case_in_gomory_cut(const mpq & a, unsigned x_j, const mpq& f0, const mpq& one_minus_f0) {
@ -111,6 +115,7 @@ class gomory::imp {
void adjust_term_and_k_for_some_ints_case_gomory(mpq &lcm_den) {
lp_assert(!m_t.is_empty());
// k = 1 + sum of m_t at bounds
auto pol = m_t.coeffs_as_vector();
m_t.clear();
if (pol.size() == 1) {
@ -131,9 +136,9 @@ class gomory::imp {
m_t.add_monomial(mpq(1), v);
}
} else {
TRACE("gomory_cut_detail", tout << "pol.size() > 1" << std::endl;);
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()) {
// normalize coefficients of integer parameters to be integers.
for (auto & pi: pol) {
@ -143,17 +148,114 @@ class gomory::imp {
m_k *= lcm_den;
}
// negate everything to return -pol <= -m_k
for (const auto & pi: pol)
for (const auto & pi: pol) {
TRACE("gomory_cut", tout << pi.first << "* " << "v" << pi.second << "\n";);
m_t.add_monomial(-pi.first, pi.second);
}
m_k.neg();
}
TRACE("gomory_cut_detail", tout << "k = " << m_k << std::endl;);
lp_assert(m_k.is_int());
}
std::string var_name(unsigned j) const {
return std::string("x") + std::to_string(j);
}
std::ostream& dump_coeff_val(std::ostream & out, const mpq & a) const {
if (a.is_int()) {
out << a;
}
else if ( a >= zero_of_type<mpq>())
out << "(/ " << numerator(a) << " " << denominator(a) << ")";
else {
out << "(- ( / " << numerator(-a) << " " << denominator(-a) << "))";
}
return out;
}
template <typename T>
void dump_coeff(std::ostream & out, const T& c) const {
out << "( * ";
dump_coeff_val(out, c.coeff());
out << " " << var_name(c.var()) << ")";
}
std::ostream& dump_row_coefficients(std::ostream & out) const {
mpq lc(1);
for (const auto& p : m_row) {
lc = lcm(lc, denominator(p.coeff()));
}
for (const auto& p : m_row) {
dump_coeff_val(out << " (* ", p.coeff()*lc) << " " << var_name(p.var()) << ")";
}
return out;
}
void dump_the_row(std::ostream& out) const {
out << "; the row, excluding fixed vars\n";
out << "(assert ( = ( +";
dump_row_coefficients(out) << ") 0))\n";
}
void dump_declarations(std::ostream& out) const {
// for a column j the var name is vj
for (const auto & p : m_row) {
out << "(declare-const " << var_name(p.var())
<< (is_int(p.var())? " Int" : " Real") << ")\n";
}
}
void dump_lower_bound_expl(std::ostream & out, unsigned j) const {
out << "(assert (>= " << var_name(j) << " " << lower_bound(j).x << "))\n";
}
void dump_upper_bound_expl(std::ostream & out, unsigned j) const {
out << "(assert (<= " << var_name(j) << " " << upper_bound(j).x << "))\n";
}
void dump_explanations(std::ostream& out) const {
for (const auto & p : m_row) {
unsigned j = p.var();
if (j == m_inf_col || (!is_real(j) && p.coeff().is_int())) {
continue;
}
else if (at_lower(j)) {
dump_lower_bound_expl(out, j);
} else {
lp_assert(at_upper(j));
dump_upper_bound_expl(out, j);
}
}
}
std::ostream& dump_term_coefficients(std::ostream & out) const {
for (const auto& p : m_t) {
dump_coeff(out, p);
}
return out;
}
std::ostream& dump_term_sum(std::ostream & out) const {
return dump_term_coefficients(out << "(+ ") << ")";
}
std::ostream& dump_term_le_k(std::ostream & out) const {
return dump_term_sum(out << "(<= ") << " " << m_k << ")";
}
void dump_the_cut_assert(std::ostream & out) const {
dump_term_le_k(out << "(assert (not ") << "))\n";
}
void dump_cut_and_constraints_as_smt_lemma(std::ostream& out) const {
dump_declarations(out);
dump_the_row(out);
dump_explanations(out);
dump_the_cut_assert(out);
out << "(check-sat)\n";
}
public:
lia_move create_cut() {
TRACE("gomory_cut",
tout << "applying cut at:\n"; m_int_solver.m_lar_solver->print_row(m_row, tout); tout << std::endl;
tout << "applying cut at:\n"; print_linear_combination_of_column_indices_only(m_row, tout); tout << std::endl;
for (auto & p : m_row) {
m_int_solver.m_lar_solver->m_mpq_lar_core_solver.m_r_solver.print_column_info(p.var(), tout);
}
@ -162,19 +264,18 @@ 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);
bool some_int_columns = false;
mpq f0 = int_solver::fractional_part(get_value(m_inf_col));
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 one_min_f0 = 1 - f0;
for (const auto & p : m_row) {
unsigned j = p.var();
#if 1
if (column_is_fixed(j)) {
m_ex.push_justification(column_lower_bound_constraint(j));
m_ex.push_justification(column_upper_bound_constraint(j));
continue;
}
#endif
if (j == m_inf_col) {
lp_assert(p.coeff() == one_of_type<mpq>());
TRACE("gomory_cut_detail", tout << "seeing basic var";);
@ -195,8 +296,10 @@ public:
if (some_int_columns)
adjust_term_and_k_for_some_ints_case_gomory(lcm_den);
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, m_k);
TRACE("gomory_cut", tout<<"gomory cut:"; m_int_solver.m_lar_solver->print_term(m_t, tout) << " <= " << m_k << std::endl;);
// TBD: validate result of subs_term_columns
TRACE("gomory_cut", print_linear_combination_of_column_indices_only(m_t, tout << "gomory cut:"); tout << " <= " << m_k << std::endl;);
return lia_move::cut;
}
imp(lar_term & t, mpq & k, explanation& ex, unsigned basic_inf_int_j, const row_strip<mpq>& row, const int_solver& int_slv ) :