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handle the case with no roots in add_zero_assumption

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
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Lev Nachmanson 2025-11-19 17:48:17 -10:00
parent 79fdb4755a
commit 7443b6e874
1 changed files with 15 additions and 15 deletions
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30
src/nlsat/nlsat_explain.cpp
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@ -290,40 +290,40 @@ namespace nlsat {
TRACE(nlsat_explain, tout << "cannot form zero assumption from constant polynomial " << q << "\n";);
return;
}
var y = max_var(q);
SASSERT(y != null_var);
if (y == null_var)
var maxx = max_var(q);
SASSERT(maxx != null_var);
if (maxx == null_var)
return;
SASSERT(m_assignment.is_assigned(y));
SASSERT(m_assignment.is_assigned(maxx));
// Substitute all assigned variables except y to obtain qsub
// and make sure its discriminant does not vanish at the model.
// Make sure its discriminant does not vanish at the model.
polynomial_ref disc(m_pm);
disc = discriminant(q, y);
disc = discriminant(q, maxx);
int const disc_sign = sign(disc);
SASSERT(disc_sign != 0);
if (disc_sign == 0)
NOT_IMPLEMENTED_YET();
undef_var_assignment partial(m_assignment, maxx);
scoped_anum_vector & roots = m_roots_tmp;
roots.reset();
// Isolate the roots of qsub by providing the assignment with y unassigned.
m_am.isolate_roots(q, undef_var_assignment(m_assignment, y), roots);
// Isolate the roots of providing the assignment with maxx unassigned.
m_am.isolate_roots(q, partial, roots);
anum const & y_val = m_assignment.value(y);
anum const & maxx_val = m_assignment.value(maxx);
unsigned root_idx = 0;
for (unsigned i = 0; i < roots.size(); ++i)
if (m_am.compare(y_val, roots[i]) == 0) {
if (m_am.compare(maxx_val, roots[i]) == 0) {
root_idx = i + 1; // roots are 1-based
break;
}
if (root_idx == 0)
return; // there are no root functions and therefore no constraints aer generated
VERIFY(root_idx > 0);
TRACE(nlsat_explain,
tout << "adding zero-assumption root literal for ";
display_var(tout, y); tout << " using root[" << root_idx << "] of " << q << "\n";);
add_root_literal(atom::ROOT_EQ, y, root_idx, q);
display_var(tout, maxx); tout << " using root[" << root_idx << "] of " << q << "\n";);
add_root_literal(atom::ROOT_EQ, maxx, root_idx, q);
}
void add_simple_assumption(atom::kind k, poly * p, bool sign = false) {