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revert to a previous state: avoid adding branches for free vars when creating a gomory cut

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
Lev Nachmanson 2018-09-13 10:10:29 -07:00
parent 822b0c1d5c
commit 0be5fc5693
5 changed files with 176 additions and 194 deletions
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37
src/util/lp/int_solver.cpp
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@ -104,10 +104,11 @@ bool int_solver::is_gomory_cut_target(const row_strip<mpq>& row) {
j = p.var();
if (!is_base(j) && (!at_bound(j) || !is_zero(get_value(j).y))) {
TRACE("gomory_cut", tout << "row is not gomory cut target:\n";
display_column(tout, j););
display_column(tout, j);
tout << "infinitesimal: " << !is_zero(get_value(j).y) << "\n";);
return false;
}
}
}
return true;
}
@ -133,11 +134,22 @@ bool int_solver::current_solution_is_inf_on_cut() const {
}
lia_move int_solver::mk_gomory_cut( unsigned inf_col, const row_strip<mpq> & row) {
lp_assert(column_is_int_inf(inf_col));
gomory gc(m_t, m_k, m_ex, inf_col, row, *this);
return gc.create_cut();
}
int int_solver::find_free_var_in_gomory_row(const row_strip<mpq>& row) {
unsigned j;
for (const auto & p : row) {
j = p.var();
if (!is_base(j) && is_free(j))
return static_cast<int>(j);
}
return -1;
}
lia_move int_solver::proceed_with_gomory_cut(unsigned j) {
const row_strip<mpq>& row = m_lar_solver->get_row(row_of_basic_column(j));
@ -147,7 +159,6 @@ lia_move int_solver::proceed_with_gomory_cut(unsigned j) {
return create_branch_on_column(j);
m_upper = true;
return mk_gomory_cut(j, row);
}
@ -375,17 +386,10 @@ lia_move int_solver::make_hnf_cut() {
#endif
lia_move r = m_hnf_cutter.create_cut(m_t, m_k, m_ex, m_upper, x0);
m_lemma->clear();
m_lemma->push_back(ineq());
ineq & f_in = first_in();
mpq k;
bool upper;
lia_move r = m_hnf_cutter.create_cut(f_in.m_term, k, *m_ex, upper, x0);
if (r == lia_move::cut) {
f_in.m_term.m_v = -k;
f_in.m_cmp = upper? lconstraint_kind::LE : GE;
if (r == lia_move::cut) {
TRACE("hnf_cut",
print_ineq(f_in, tout << "cut:");
m_lar_solver->print_term(*m_t, tout << "cut:");
tout << " <= " << *m_k << std::endl;
for (unsigned i : m_hnf_cutter.constraints_for_explanation()) {
m_lar_solver->print_constraint(i, tout);
}
@ -866,7 +870,7 @@ bool int_solver::at_bound(unsigned j) const {
case column_type::upper_bound:
return mpq_solver.m_upper_bounds[j] == get_value(j);
default:
return true; // a free var is always at a bound
return false;
}
}
@ -1004,18 +1008,19 @@ lia_move int_solver::create_branch_on_column(int j) {
TRACE("check_main_int", tout << "branching" << std::endl;);
lp_assert(m_t.is_empty());
lp_assert(j != -1);
first_in().add_coeff_var(mpq(1), m_lar_solver->adjust_column_index_to_term_index(j));
m_t->add_coeff_var(mpq(1), m_lar_solver->adjust_column_index_to_term_index(j));
if (is_free(j)) {
m_upper = true;
m_k = mpq(0);
} else {
m_upper = left_branch_is_more_narrow_than_right(j);
m_k = m_upper? floor(get_value(j)) : ceil(get_value(j));
m_k = *m_upper? floor(get_value(j)) : ceil(get_value(j));
}
TRACE("int_solver", tout << "branching v" << j << " = " << get_value(j) << "\n";
display_column(tout, j);
tout << "k = " << m_k << std::endl;
);
return lia_move::branch;