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add branch / cut selection heuristic from solver=2

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disabled for testing.
This commit is contained in:
Nikolaj Bjorner 2023-04-10 22:14:03 -07:00
parent bb44b91e45
commit 368d60f553
6 changed files with 114 additions and 12 deletions
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69
src/math/lp/int_solver.cpp
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@ -632,4 +632,73 @@ bool int_solver::non_basic_columns_are_at_bounds() const {
return true;
}
int int_solver::select_int_infeasible_var() {
int result = -1;
mpq range;
mpq new_range;
mpq small_value(1024);
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;
enum state { small_box, is_small_value, any_value, not_found };
state st = not_found;
// 1. small box
// 2. small value
// 3. any value
for (; k < lra.r_basis().size(); k++) {
j = lra.r_basis()[k];
if (!column_is_int_inf(j))
continue;
usage = lra.usage_in_terms(j);
if (is_boxed(j) && (new_range = lcs.m_r_upper_bounds()[j].x - lcs.m_r_lower_bounds()[j].x - rational(2*usage)) <= small_value) {
SASSERT(!is_fixed(j));
if (st != small_box) {
n = 0;
st = small_box;
}
if (n == 0 || new_range < range) {
result = j;
range = new_range;
n = 1;
}
else if (new_range == range && (random() % (++n) == 0)) {
result = j;
}
continue;
}
if (st == small_box)
continue;
impq const& value = get_value(j);
if (abs(value.x) < small_value ||
(has_upper(j) && small_value > upper_bound(j).x - value.x) ||
(has_lower(j) && small_value > value.x - lower_bound(j).x)) {
if (st != is_small_value) {
n = 0;
st = is_small_value;
}
if (random() % (++n) == 0)
result = j;
}
if (st == is_small_value)
continue;
SASSERT(st == not_found || st == any_value);
st = any_value;
if (n == 0 /*|| usage > prev_usage*/) {
result = j;
prev_usage = usage;
n = 1;
}
else if (usage > 0 && /*usage == prev_usage && */ (random() % (++n) == 0))
result = j;
}
return result;
}
}