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fix dependencies for Gomory polarity

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
Lev Nachmanson 2024-01-13 19:01:21 -10:00
parent 2eadcf0872
commit e2fb4fbd38
2 changed files with 30 additions and 14 deletions
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42
src/math/lp/gomory.cpp
View file

@ -69,14 +69,16 @@ struct create_cut {
// here we have the product of new_a*(xj - lb(j)), so new_a*lb(j) is added to m_k
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_k.addmul(new_a, lower_bound(j).x);
push_explanation(column_lower_bound_constraint(j));
}
else {
lp_assert(at_upper(j));
// here we have the expression new_a*(xj - ub), so new_a*ub(j) is added to m_k
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_k.addmul(new_a, upper_bound(j).x);
push_explanation(column_upper_bound_constraint(j));
}
m_t.add_monomial(new_a, j);
TRACE("gomory_cut_detail", tout << "new_a = " << new_a << ", k = " << m_k << "\n";);
@ -286,21 +288,14 @@ public:
m_one_minus_fj = 1 - m_fj;
int_case_in_gomory_cut(j);
}
bool lb = at_lower(j);
if (lb) {
push_explanation(column_lower_bound_constraint(j));
} else {
SASSERT(at_upper(j));
push_explanation(column_upper_bound_constraint(j));
}
if (p.coeff().is_pos()) {
if (lb)
if (at_lower(j))
set_polarity(row_polarity::MAX);
else
set_polarity(row_polarity::MIN);
}
else {
if (lb)
if (at_lower(j))
set_polarity(row_polarity::MIN);
else
set_polarity(row_polarity::MAX);
@ -440,6 +435,27 @@ public:
return ret;
}
u_dependency* gomory::add_deps(u_dependency* dep, const row_strip<mpq>& row, lpvar basic_var) {
u_dependency* ret = dep;
for (const auto& p : row) {
lpvar j = p.var();
if (j == basic_var)
continue;
if (lia.is_fixed(j))
continue;
if (lia.is_real(j)) continue;
if (!p.coeff().is_int()) continue;
// the explanation for all above have been already added
if (lia.at_lower(j))
ret = lia.lra.dep_manager().mk_join(lia.column_lower_bound_constraint(j), ret);
else {
SASSERT(lia.at_upper(j));
ret = lia.lra.dep_manager().mk_join(lia.column_upper_bound_constraint(j), ret);
}
}
return ret;
}
lia_move gomory::get_gomory_cuts(unsigned num_cuts) {
struct cut_result {lar_term t; mpq k; u_dependency *dep;};
vector<cut_result> big_cuts;
@ -478,9 +494,9 @@ public:
}
SASSERT(test_row_polarity(lia, row, j) == cc.m_polarity);
if (cc.m_polarity == row_polarity::MAX)
lra.update_column_type_and_bound(j, lp::lconstraint_kind::LE, floor(lra.get_column_value(j).x), cc.m_dep);
lra.update_column_type_and_bound(j, lp::lconstraint_kind::LE, floor(lra.get_column_value(j).x), add_deps(cc.m_dep, row, j));
else if (cc.m_polarity == row_polarity::MIN)
lra.update_column_type_and_bound(j, lp::lconstraint_kind::GE, ceil(lra.get_column_value(j).x), cc.m_dep);
lra.update_column_type_and_bound(j, lp::lconstraint_kind::GE, ceil(lra.get_column_value(j).x), add_deps(cc.m_dep, row, j));
if (!is_small_cut(lia.m_t)) {
big_cuts.push_back({cc.m_t, cc.m_k, cc.m_dep});

2
src/math/lp/gomory.h
View file

@ -30,7 +30,7 @@ namespace lp {
lia_move cut(lar_term & t, mpq & k, explanation* ex, unsigned basic_inf_int_j, const row_strip<mpq>& row);
unsigned_vector gomory_select_int_infeasible_vars(unsigned num_cuts);
bool is_gomory_cut_target(lpvar j);
lia_move get_cut(lpvar j);
u_dependency* add_deps(u_dependency*, const row_strip<mpq>&, lpvar);
public:
lia_move get_gomory_cuts(unsigned num_cuts);
gomory(int_solver& lia);