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add scaffolding for experiments with slack

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This commit is contained in:
Nikolaj Bjorner 2025-04-23 17:07:50 -07:00
parent 12ccf59ab9
commit fe1fff3b7e
2 changed files with 55 additions and 2 deletions
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8
src/math/lp/column.h
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@ -40,6 +40,8 @@ class lar_term; // forward definition
class column {
u_dependency* m_lower_bound_witness = nullptr;
u_dependency* m_upper_bound_witness = nullptr;
unsigned m_previous_lower = UINT_MAX;
unsigned m_previous_upper = UINT_MAX;
lar_term* m_term = nullptr;
public:
lar_term* term() const { return m_term; }
@ -50,6 +52,12 @@ public:
u_dependency* lower_bound_witness() const { return m_lower_bound_witness; }
u_dependency* upper_bound_witness() const { return m_upper_bound_witness; }
unsigned previous_lower() const { return m_previous_lower; }
unsigned previous_upper() const { return m_previous_upper; }
void set_previous_lower(unsigned j) { m_previous_lower = j; }
void set_previous_upper(unsigned j) { m_previous_upper = j; }
column() {}
column(lar_term* term) : m_term(term) {}

49
src/math/lp/lar_solver.cpp
View file

@ -589,17 +589,23 @@ namespace lp {
};
void lar_solver::set_upper_bound_witness(lpvar j, u_dependency* dep, impq const& high) {
bool has_upper = m_columns[j].upper_bound_witness() != nullptr;
m_column_updates.push_back({true, j, get_upper_bound(j), m_columns[j]});
m_trail.push(column_update_trail(*this));
m_columns[j].set_upper_bound_witness(dep);
if (has_upper)
m_columns[j].set_previous_upper(m_column_updates.size() - 1);
m_mpq_lar_core_solver.m_r_upper_bounds[j] = high;
insert_to_columns_with_changed_bounds(j);
}
void lar_solver::set_lower_bound_witness(lpvar j, u_dependency* dep, impq const& low) {
bool has_lower = m_columns[j].lower_bound_witness() != nullptr;
m_column_updates.push_back({false, j, get_lower_bound(j), m_columns[j]});
m_trail.push(column_update_trail(*this));
m_columns[j].set_lower_bound_witness(dep);
if (has_lower)
m_columns[j].set_previous_lower(m_column_updates.size() - 1);
m_mpq_lar_core_solver.m_r_lower_bounds[j] = low;
insert_to_columns_with_changed_bounds(j);
}
@ -1169,11 +1175,50 @@ namespace lp {
const vector<std::pair<mpq, unsigned>>& inf_row,
int inf_sign) const {
#if 0
impq slack(0);
for (auto& [coeff, j] : inf_row) {
int adj_sign = coeff.is_pos() ? inf_sign : -inf_sign;
const column& ul = m_columns[j];
slack += coeff * (adj_sign < 0 ? get_upper_bound(j) : get_lower_bound(j));
}
bool is_pos = slack.is_pos();
#endif
for (auto& [coeff, j] : inf_row) {
int adj_sign = coeff.is_pos() ? inf_sign : -inf_sign;
bool is_upper = adj_sign < 0;
const column& ul = m_columns[j];
u_dependency* bound_constr_i = is_upper ? ul.upper_bound_witness() : ul.lower_bound_witness();
#if 0
if (false)
;
else if(is_upper) {
if (ul.previous_upper() != UINT_MAX) {
auto const& [_is_upper, _j, _bound, _column] = m_column_updates[ul.previous_upper()];
auto new_slack = slack + coeff * (_bound - get_upper_bound(j));
if (is_pos == new_slack.is_pos()) {
//verbose_stream() << "can weaken j" << j << " " << coeff << " " << get_upper_bound(j) << " " << _bound << "\n";
slack = new_slack;
bound_constr_i = _column.upper_bound_witness();
}
}
}
else {
if (ul.previous_lower() != UINT_MAX) {
auto const& [_is_upper, _j, _bound, _column] = m_column_updates[ul.previous_lower()];
auto new_slack = slack + coeff * (_bound - get_lower_bound(j));
if (is_pos == new_slack.is_pos()) {
//verbose_stream() << "can weaken j" << j << " " << coeff << " " << get_lower_bound(j) << " " << _bound << "\n";
slack = new_slack;
bound_constr_i = _column.lower_bound_witness();
}
}
}
#endif
u_dependency* bound_constr_i = adj_sign < 0 ? ul.upper_bound_witness() : ul.lower_bound_witness();
svector<constraint_index> deps;
m_dependencies.linearize(bound_constr_i, deps);
for (auto d : deps) {