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Nikolaj's fix in add_zero_assumption

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
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Lev Nachmanson 2024-03-19 09:42:36 -10:00 • committed by Lev Nachmanson
parent a9054bc73b
commit 730f9ad9b7
1 changed files with 73 additions and 2 deletions
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75
src/nlsat/nlsat_explain.cpp
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@ -277,11 +277,13 @@ namespace nlsat {
}
};
void add_zero_assumption(polynomial_ref & p) {
void add_zero_assumption(polynomial_ref& p) {
// If p is of the form p1^n1 * ... * pk^nk,
// then only the factors that are zero in the current interpretation needed to be considered.
// I don't want to create a nested conjunction in the clause.
// Then, I assert p_i1 * ... * p_im != 0
bool is_linear = true;
unsigned x = max_var(p);
{
restore_factors _restore(m_factors, m_factors_save);
factor(p, m_factors);
@ -294,14 +296,37 @@ namespace nlsat {
if (is_zero(sign(f))) {
m_zero_fs.push_back(m_factors.get(i));
m_is_even.push_back(false);
}
is_linear &= m_pm.degree(f, x) <= 1;
}
}
}
if (!is_linear) {
scoped_anum_vector& roots = m_roots_tmp;
roots.reset();
m_am.isolate_roots(p, undef_var_assignment(m_assignment, x), roots);
unsigned num_roots = roots.size();
if (num_roots > 0) {
anum const& x_val = m_assignment.value(x);
for (unsigned i = 0; i < num_roots; i++) {
int s = m_am.compare(x_val, roots[i]);
if (s != 0)
continue;
add_root_literal(atom::ROOT_EQ, x, i + 1, p);
return;
}
display(verbose_stream() << "polynomial ", p);
m_solver.display(verbose_stream());
UNREACHABLE();
}
}
SASSERT(!m_zero_fs.empty()); // one of the factors must be zero in the current interpretation, since p is zero in it.
literal l = m_solver.mk_ineq_literal(atom::EQ, m_zero_fs.size(), m_zero_fs.data(), m_is_even.data());
l.neg();
TRACE("nlsat_explain", tout << "adding (zero assumption) literal:\n"; display(tout, l); tout << "\n";);
add_literal(l);
}
void add_simple_assumption(atom::kind k, poly * p, bool sign = false) {
@ -649,6 +674,52 @@ namespace nlsat {
}
}
void add_zero_assumption_on_factor(polynomial_ref& f) {
display(std::cout << "zero factors \n", f);
}
// this function also explains the value 0, if met
bool coeffs_are_zeroes(polynomial_ref &s) {
restore_factors _restore(m_factors, m_factors_save);
factor(s, m_factors);
unsigned num_factors = m_factors.size();
m_zero_fs.reset();
m_is_even.reset();
polynomial_ref f(m_pm);
bool have_zero = false;
for (unsigned i = 0; i < num_factors; i++) {
f = m_factors.get(i);
// std::cout << "f=";display(std::cout, f) << "\n";
if (coeffs_are_zeroes_in_factor(f)) {
have_zero = true;
break;
}
}
if (!have_zero)
return false;
var x = max_var(f);
unsigned n = degree(f, x);
auto c = polynomial_ref(this->m_pm);
for (unsigned j = 0; j <= n; j++) {
c = m_pm.coeff(s, x, j);
SASSERT(sign(c) == 0);
ensure_sign(c);
}
return true;
}
bool coeffs_are_zeroes_in_factor(polynomial_ref & s) {
var x = max_var(s);
unsigned n = degree(s, x);
auto c = polynomial_ref(this->m_pm);
for (unsigned j = 0; j <= n; j++) {
c = m_pm.coeff(s, x, j);
if (sign(c) != 0)
return false;
}
return true;
}
/**
\brief Add v-psc(p, q, x) into m_todo
*/