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try evaluate discriminants more rarely

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
Lev Nachmanson 2026-02-20 10:16:27 -10:00
parent e2129a7b81
commit 66aaece3f5
1 changed files with 32 additions and 13 deletions
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45
src/nlsat/levelwise.cpp
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@ -300,7 +300,7 @@ namespace nlsat {
polynomial_ref dq = derivative(q, x);
if (!dq || is_zero(dq) || is_const(dq))
continue;
if (m_am.eval_sign_at(dq, sample()) != 0) {
if (sign(dq)) {
request_factorized(dq);
return;
}
@ -405,7 +405,7 @@ namespace nlsat {
coeff = m_pm.coeff(p, x, j);
if (!coeff || is_zero(coeff))
continue;
if (m_am.eval_sign_at(coeff, sample()) == 0)
if (sign(coeff) == 0)
continue;
unsigned td = total_degree(coeff);
@ -424,25 +424,44 @@ namespace nlsat {
return best;
}
::sign sign(polynomial_ref const & p) {
return ::nlsat::sign(p, m_solver.sample(), m_am);
}
void add_projection_for_poly(polynomial_ref const& p, unsigned x, polynomial_ref const& nonzero_coeff, bool add_leading_coeff, bool add_discriminant) {
TRACE(lws,
TRACE(lws,
m_pm.display(tout << " add_projection_for_poly: p=", p)
<< " x=" << x << " add_lc=" << add_leading_coeff << " add_disc=" << add_discriminant << "\n";
);
// Line 11 (non-null witness coefficient)
if (nonzero_coeff && !is_const(nonzero_coeff))
request_factorized(nonzero_coeff);
// Line 12 (disc + leading coefficient)
if (add_discriminant)
request_factorized(psc_discriminant(p, x));
bool add_nzero_coeff = nonzero_coeff && !is_const(nonzero_coeff);
if (add_leading_coeff) {
unsigned deg = m_pm.degree(p, x);
polynomial_ref lc(m_pm);
lc = m_pm.coeff(p, x, deg);
TRACE(lws, m_pm.display(tout << " adding lc: ", lc) << "\n";);
request_factorized(lc);
if (add_nzero_coeff && lc && sign(lc))
add_nzero_coeff = false;
}
if (add_discriminant) {
polynomial_ref disc(m_pm);
disc = psc_discriminant(p, x);
if (disc) {
request_factorized(disc);
// If p is nullified at some point then at this point discriminant well be evaluated
// to zero, as can be seen from the Sylvester matrix which would
// have at least one zero row.
if (add_nzero_coeff && sign(disc)) // we can avoid adding a nonzero_coeff if sign(disc) != 0
add_nzero_coeff = false;
}
}
if (add_nzero_coeff)
request_factorized(nonzero_coeff);
}
// ============================================================================
@ -1026,7 +1045,7 @@ namespace nlsat {
TRACE(lws,
tout << " resultant poly: ";
if (res)
m_pm.display(tout, res) << "\n resultant sign at sample: " << m_am.eval_sign_at(res, sample());
m_pm.display(tout, res) << "\n resultant sign at sample: " << sign(res);
else
tout << "(null)";
tout << "\n";
@ -1146,7 +1165,7 @@ namespace nlsat {
// No need for an additional coefficient witness in this case.
polynomial_ref witness = m_witnesses[i];
if (add_lc && witness && !is_const(witness))
if (lc && !is_zero(lc) && m_am.eval_sign_at(lc, sample()) != 0)
if (lc && !is_zero(lc) && sign(lc))
witness = polynomial_ref(m_pm);
add_projection_for_poly(p, m_level, witness, add_lc, add_disc);
@ -1290,14 +1309,14 @@ namespace nlsat {
bool add_lc = true;
if (!poly_has_roots(i))
if (lc && !is_zero(lc) && m_am.eval_sign_at(lc, sample()) != 0)
if (lc && !is_zero(lc) && sign(lc))
add_lc = false;
// if the leading coefficient is already non-zero at the sample
// AND we're adding lc, we do not need to project an additional non-null coefficient witness.
polynomial_ref witness = m_witnesses[i];
if (add_lc && witness && !is_const(witness))
if (lc && !is_zero(lc) && m_am.eval_sign_at(lc, sample()) != 0)
if (lc && !is_zero(lc) && sign(lc))
witness = polynomial_ref(m_pm); // zero the witnsee as lc will be the witness
add_projection_for_poly(p, m_n, witness, add_lc, true); //true to add the discriminant
}