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fix #2949 fix #2955 experiment with cut selection

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2020-02-08 10:34:14 -08:00
parent 140926e7c0
commit f29b455611
7 changed files with 74 additions and 41 deletions
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55
src/math/lp/int_solver.cpp
View file

@ -37,6 +37,55 @@ bool int_solver::has_inf_int() const {
return m_lar_solver->has_inf_int();
}
int int_solver::find_gomory_cut_column() {
int result = -1;
unsigned n = 0;
bool boxed = false;
unsigned min_row_size = UINT_MAX;
mpq min_range;
// Prefer smaller row size
#if 0
// Prefer boxed to non-boxed
// Prefer smaller ranges
#endif
for (unsigned j : m_lar_solver->r_basis()) {
if (!column_is_int_inf(j))
continue;
const row_strip<mpq>& row = m_lar_solver->get_row(row_of_basic_column(j));
if (!is_gomory_cut_target(row))
continue;
#if 1
if (is_boxed(j) && (min_row_size == UINT_MAX || 4*row.size() < 5*min_row_size)) {
lar_core_solver & lcs = m_lar_solver->m_mpq_lar_core_solver;
auto new_range = lcs.m_r_upper_bounds()[j].x - lcs.m_r_lower_bounds()[j].x;
if (!boxed) {
result = j;
n = 1;
min_row_size = row.size();
boxed = true;
min_range = new_range;
continue;
}
if (min_range > 2*new_range || ((5*min_range > 4*new_range && (random() % (++n)) == 0))) {
result = j;
n = 1;
min_row_size = row.size();
min_range = std::min(min_range, new_range);
continue;
}
}
#endif
if (min_row_size == UINT_MAX || (4*row.size() < 5*min_row_size && random() % (++n) == 0)) {
result = j;
n = 1;
min_row_size = std::min(min_row_size, row.size());
}
}
return result;
}
int int_solver::find_inf_int_base_column() {
unsigned inf_int_count = 0;
int j = find_inf_int_boxed_base_column_with_smallest_range(inf_int_count);
@ -304,7 +353,8 @@ lia_move int_solver::gomory_cut() {
lp_assert(st == lp_status::FEASIBLE || st == lp_status::OPTIMAL);
}
int j = find_inf_int_base_column();
// int j = find_inf_int_base_column();
int j = find_gomory_cut_column();
if (j == -1) {
j = find_inf_int_nbasis_column();
return j == -1? lia_move::sat : create_branch_on_column(j);
@ -1019,7 +1069,8 @@ lia_move int_solver::create_branch_on_column(int j) {
if (is_free(j)) {
m_upper = random() % 2;
m_k = mpq(0);
} else {
}
else {
m_upper = left_branch_is_more_narrow_than_right(j);
m_k = m_upper? floor(get_value(j)) : ceil(get_value(j));
}

1
src/math/lp/int_solver.h
View file

@ -107,6 +107,7 @@ private:
lia_move branch_or_sat();
int find_any_inf_int_column_basis_first();
int find_inf_int_base_column();
int find_gomory_cut_column();
int find_inf_int_boxed_base_column_with_smallest_range(unsigned&);
int get_kth_inf_int(unsigned) const;
lp_settings& settings();

9
src/math/lp/lar_constraints.h
View file

@ -158,10 +158,6 @@ public:
}
void pop(unsigned k) {
m_constraint_count.pop(k);
for (unsigned i = m_constraints.size(); i-- > m_constraint_count; )
m_constraints[i]->~lar_base_constraint();
m_constraints.shrink(m_constraint_count);
#if 1
m_active_lim.pop(k);
for (unsigned i = m_active.size(); i-- > m_active_lim; ) {
@ -169,6 +165,11 @@ public:
}
m_active.shrink(m_active_lim);
#endif
m_constraint_count.pop(k);
for (unsigned i = m_constraints.size(); i-- > m_constraint_count; )
m_constraints[i]->~lar_base_constraint();
m_constraints.shrink(m_constraint_count);
m_region.pop_scope(k);
}