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perf in branching (#4719)

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
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Lev Nachmanson 2020-09-29 22:05:16 -07:00 • committed by GitHub
parent a414480274
commit 4e74c4cdd4
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2 changed files with 14 additions and 8 deletions
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20
src/math/lp/int_branch.cpp
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@ -25,7 +25,8 @@ namespace lp {
int_branch::int_branch(int_solver& lia):lia(lia), lra(lia.lra) {}
lia_move int_branch::operator()() {
int j = find_inf_int_column();
lra.move_non_basic_columns_to_bounds(true);
int j = find_inf_int_base_column();
return j == -1? lia_move::sat : create_branch_on_column(j);
}
@ -50,7 +51,7 @@ lia_move int_branch::create_branch_on_column(int j) {
}
int int_branch::find_inf_int_column() {
int int_branch::find_inf_int_base_column() {
int result = -1;
mpq range;
mpq new_range;
@ -58,16 +59,19 @@ int int_branch::find_inf_int_column() {
unsigned n = 0;
lar_core_solver & lcs = lra.m_mpq_lar_core_solver;
unsigned prev_usage = 0; // to quiet down the compile
unsigned k = 0;
unsigned usage;
unsigned j = 0;
unsigned j;
// this loop looks for a column with the most usages, but breaks when
// a column with a small span of bounds is found
for (; j < lra.column_count(); j++) {
for (; k < lra.r_basis().size(); k++) {
j = lra.r_basis()[k];
if (!lia.column_is_int_inf(j))
continue;
usage = lra.usage_in_terms(j);
if (lia.is_boxed(j) && (range = lcs.m_r_upper_bounds()[j].x - lcs.m_r_lower_bounds()[j].x - rational(2*usage)) <= small_range_thresold) {
result = j++;
result = j;
k++;
n = 1;
break;
}
@ -79,11 +83,13 @@ int int_branch::find_inf_int_column() {
result = j;
}
}
SASSERT(k == lra.r_basis().size() || n == 1);
// this loop looks for boxed columns with a small span
for (; j < lra.column_count(); j++) {
for (; k < lra.r_basis().size(); k++) {
j = lra.r_basis()[k];
if (!lia.column_is_int_inf(j) || !lia.is_boxed(j))
continue;
SASSERT(!lia.is_fixed(j));
usage = lra.usage_in_terms(j);
new_range = lcs.m_r_upper_bounds()[j].x - lcs.m_r_lower_bounds()[j].x - rational(2*usage);
if (new_range < range) {

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

@ -28,7 +28,7 @@ namespace lp {
class int_solver& lia;
class lar_solver& lra;
lia_move create_branch_on_column(int j);
int find_inf_int_column();
int find_inf_int_base_column();
public:
int_branch(int_solver& lia);