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add option to control epsilon #7791

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#7791 reports on using model values during lex optimization that break soft constraints.
This is an artifact of using optimization where optimal values can be arbitrarily close to a rational.
In a way it is by design, but we give the user now an option to control the starting point for epsilon when converting infinitesimals into rationals.
This commit is contained in:
Nikolaj Bjorner 2025-08-17 16:47:23 -07:00
parent d8bf0e047f
commit c75b8ec752
7 changed files with 14 additions and 4 deletions
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6
src/math/lp/lar_solver.cpp
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@ -1523,7 +1523,7 @@ namespace lp {
if (!m_imp->m_columns_with_changed_bounds.empty())
return false;
m_imp->m_delta = get_core_solver().find_delta_for_strict_bounds(mpq(1));
m_imp->m_delta = get_core_solver().find_delta_for_strict_bounds(m_imp->m_settings.m_epsilon);
unsigned j;
unsigned n = get_core_solver().r_x().size();
do {
@ -1545,7 +1545,7 @@ namespace lp {
}
void lar_solver::get_model_do_not_care_about_diff_vars(std::unordered_map<lpvar, mpq>& variable_values) const {
mpq delta = get_core_solver().find_delta_for_strict_bounds(mpq(1));
mpq delta = get_core_solver().find_delta_for_strict_bounds(m_imp->m_settings.m_epsilon);
for (unsigned i = 0; i < get_core_solver().r_x().size(); i++) {
const impq& rp = get_core_solver().r_x(i);
variable_values[i] = rp.x + delta * rp.y;
@ -1569,7 +1569,7 @@ namespace lp {
}
if (y_is_zero)
return;
mpq delta = get_core_solver().find_delta_for_strict_bounds(mpq(1));
mpq delta = get_core_solver().find_delta_for_strict_bounds(m_imp->m_settings.m_epsilon);
for (unsigned j = 0; j < number_of_vars(); j++) {
auto& v = get_core_solver().r_x(j);
if (!v.y.is_zero()) {

2
src/math/lp/lp_settings.cpp
View file

@ -34,6 +34,8 @@ void lp::lp_settings::updt_params(params_ref const& _p) {
report_frequency = p.arith_rep_freq();
m_simplex_strategy = static_cast<lp::simplex_strategy_enum>(p.arith_simplex_strategy());
m_nlsat_delay = p.arith_nl_delay();
auto eps = p.arith_epsilon();
m_epsilon = rational(std::max(1, (int)(100000*eps)), 100000);
m_dio = lp_p.dio();
m_dio_enable_gomory_cuts = lp_p.dio_cuts_enable_gomory();
m_dio_enable_hnf_cuts = lp_p.dio_cuts_enable_hnf();

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

@ -242,6 +242,7 @@ private:
public:
unsigned limit_on_rows_for_hnf_cutter = 75;
unsigned limit_on_columns_for_hnf_cutter = 150;
mpq m_epsilon = mpq(1);
private:
unsigned m_nlsat_delay = 0;
bool m_enable_hnf = true;