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fix box mode: isolate m_lower/m_upper between objectives

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geometric_lex's update_lower_lex updates m_lower for all subsequent
objectives with saved values from the current model. In box mode this
contaminates later objectives' starting bounds, causing platform-dependent
results. Save and restore m_lower/m_upper across iterations so each
objective starts from a clean state.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This commit is contained in:
Lev Nachmanson 2026-03-19 12:31:24 -10:00 • committed by Lev Nachmanson
parent acd2e9475d
commit 1c70b9e6ee
1 changed files with 13 additions and 0 deletions
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13
src/opt/optsmt.cpp
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@ -544,16 +544,29 @@ namespace opt {
// Note: geometric_lex is used unconditionally here, even when
// m_optsmt_engine is "symba", because symba_opt and geometric_opt
// optimize all objectives jointly, violating box mode semantics.
//
// Save and restore m_lower/m_upper across iterations because
// geometric_lex's update_lower_lex updates m_lower for all
// subsequent objectives with saved values from the current model,
// which would contaminate later objectives' starting bounds.
vector<inf_eps> saved_lower(m_lower);
vector<inf_eps> saved_upper(m_upper);
m_context.get_base_model(m_best_model);
for (unsigned i = 0; i < m_vars.size() && m.inc(); ++i) {
m_lower = saved_lower;
m_upper = saved_upper;
solver::scoped_push _push(*m_s);
is_sat = geometric_lex(i, true, true);
if (is_sat == l_undef)
return l_undef;
if (is_sat == l_false)
return l_false;
saved_lower[i] = m_lower[i];
saved_upper[i] = m_upper[i];
m_models.set(i, m_best_model.get());
}
m_lower = saved_lower;
m_upper = saved_upper;
return l_true;
}