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move branch functionality to int_branch

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2026-07-28 10:54:04 -07:00
parent 318738b309
commit 31cff62a26
2 changed files with 61 additions and 123 deletions
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106
src/math/lp/int_branch.cpp
View file

@ -52,62 +52,76 @@ lia_move int_branch::create_branch_on_column(int j) {
int int_branch::find_inf_int_base_column() {
#if 1
return lia.select_int_infeasible_var();
#endif
int result = -1;
int r_small_box = -1;
int r_small_value = -1;
int r_any_value = -1;
unsigned n_small_box = 1;
unsigned n_small_value = 1;
unsigned n_any_value = 1;
mpq range;
mpq new_range;
mpq small_value(1024);
unsigned n = 0;
lar_core_solver & lcs = lra.get_core_solver();
unsigned prev_usage = 0; // to quiet down the compiler
unsigned k = 0;
unsigned usage;
unsigned j;
mpq min_any_value;
unsigned prev_usage = 0;
// this loop looks for a column with the most usages, but breaks when
// a column with a small span of bounds is found
for (; k < lra.r_basis().size(); ++k) {
j = lra.r_basis()[k];
auto add_column = [&](bool improved, int &result, unsigned &n, unsigned j) {
if (result == -1)
result = j;
else if (improved && ((random() % (++n)) == 0))
result = j;
};
for (unsigned j : lra.r_basis()) {
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_value) {
result = j;
k++;
n = 1;
break;
if (lia.settings().get_cancel_flag()) {
return -1;
}
if (n == 0 || usage > prev_usage) {
result = j;
prev_usage = usage;
n = 1;
} else if (usage == prev_usage && (lia.settings().random_next() % (++n) == 0)) {
result = j;
}
}
SASSERT(k == lra.r_basis().size() || n == 1);
// this loop looks for boxed columns with a small span
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) {
n = 1;
result = j;
range = new_range;
} else if (new_range == range && (lia.settings().random_next() % (++n) == 0)) {
result = j;
unsigned usage = lra.usage_in_terms(j);
if (lia.is_boxed(j) && (new_range = lra.bound_span_x(j) - rational(2 * usage)) <= small_value) {
bool improved = new_range <= range || r_small_box == -1;
if (improved)
range = new_range;
add_column(improved, r_small_box, n_small_box, j);
continue;
}
impq const &value = lia.get_value(j);
if (abs(value.x) < small_value || (lra.column_has_upper_bound(j) && small_value > lia.upper_bound(j).x - value.x) ||
(lia.has_lower(j) && small_value > value.x - lia.lower_bound(j).x)) {
TRACE(int_solver, tout << "small j" << j << "\n");
add_column(true, r_small_value, n_small_value, j);
continue;
}
TRACE(int_solver, tout << "any j" << j << "\n");
// Among columns with a large value, prefer the one whose
// absolute value is smallest to avoid branching on ever
// larger integers when better (smaller) options are available.
mpq const abs_value = abs(value.x);
if (r_any_value == -1 || abs_value < min_any_value) {
r_any_value = j;
min_any_value = abs_value;
n_any_value = 1;
prev_usage = usage;
}
else if (abs_value == min_any_value) {
add_column(usage >= prev_usage, r_any_value, n_any_value, j);
if (usage > prev_usage)
prev_usage = usage;
}
}
return result;
if (r_small_box != -1 && (lra.settings().random_next() % 3 != 0))
return r_small_box;
if (r_small_value != -1 && (lra.settings().random_next() % 3) != 0)
return r_small_value;
if (r_any_value != -1)
return r_any_value;
if (r_small_box != -1)
return r_small_box;
return r_small_value;
}
}

78
src/math/lp/int_solver.cpp
View file

@ -322,81 +322,7 @@ namespace lp {
tout << "term:";lra.print_term(m_t, tout) << "\n";
);
return v * sign > impq(m_k) * sign;
}
int select_int_infeasible_var() {
int r_small_box = -1;
int r_small_value = -1;
int r_any_value = -1;
unsigned n_small_box = 1;
unsigned n_small_value = 1;
unsigned n_any_value = 1;
mpq range;
mpq new_range;
mpq small_value(1024);
mpq min_any_value;
unsigned prev_usage = 0;
auto add_column = [&](bool improved, int& result, unsigned& n, unsigned j) {
if (result == -1)
result = j;
else if (improved && ((random() % (++n)) == 0))
result = j;
};
for (unsigned j : lra.r_basis()) {
if (!column_is_int_inf(j))
continue;
if (settings().get_cancel_flag()){
return -1;
}
SASSERT(!lia.is_fixed(j));
unsigned usage = lra.usage_in_terms(j);
if (lia.is_boxed(j) && (new_range = lra.bound_span_x(j) - rational(2*usage)) <= small_value) {
bool improved = new_range <= range || r_small_box == -1;
if (improved)
range = new_range;
add_column(improved, r_small_box, n_small_box, j);
continue;
}
impq const& value = lia.get_value(j);
if (abs(value.x) < small_value ||
(lra.column_has_upper_bound(j) && small_value > upper_bound(j).x - value.x) ||
(has_lower(j) && small_value > value.x - lower_bound(j).x)) {
TRACE(int_solver, tout << "small j" << j << "\n");
add_column(true, r_small_value, n_small_value, j);
continue;
}
TRACE(int_solver, tout << "any j" << j << "\n");
// Among columns with a large value, prefer the one whose
// absolute value is smallest to avoid branching on ever
// larger integers when better (smaller) options are available.
mpq const abs_value = abs(value.x);
if (r_any_value == -1 || abs_value < min_any_value) {
r_any_value = j;
min_any_value = abs_value;
n_any_value = 1;
prev_usage = usage;
}
else if (abs_value == min_any_value) {
add_column(usage >= prev_usage, r_any_value, n_any_value, j);
if (usage > prev_usage)
prev_usage = usage;
}
}
if (r_small_box != -1 && (random() % 3 != 0))
return r_small_box;
if (r_small_value != -1 && (random() % 3) != 0)
return r_small_value;
if (r_any_value != -1)
return r_any_value;
if (r_small_box != -1)
return r_small_box;
return r_small_value;
}
}
std::ostream & display_row(std::ostream & out, lp::row_strip<rational> const & row) const {
bool first = true;
@ -969,8 +895,6 @@ namespace lp {
return m_imp->has_upper(j);
}
int int_solver::select_int_infeasible_var() { return m_imp->select_int_infeasible_var(); }
bool int_solver::current_solution_is_inf_on_cut() const { return m_imp->current_solution_is_inf_on_cut(); }
const impq & int_solver::lower_bound(unsigned j) const { return m_imp->lower_bound(j);}
const impq & int_solver::upper_bound(unsigned j) const { return m_imp->upper_bound(j);}
#if Z3DEBUG