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Add GCD test

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This commit is contained in:
Nikolaj Bjorner 2020-11-20 11:09:31 -08:00
parent b7b7970c4a
commit 6506d33b35
3 changed files with 46 additions and 5 deletions
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38
src/ast/rewriter/poly_rewriter_def.h
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@ -445,7 +445,7 @@ inline expr * poly_rewriter<Config>::get_power_product(expr * t, numeral & a) {
}
template<typename Config>
bool poly_rewriter<Config>::is_mul(expr * t, numeral & c, expr * & pp) {
bool poly_rewriter<Config>::is_mul(expr * t, numeral & c, expr * & pp) const {
if (!is_mul(t) || to_app(t)->get_num_args() != 2)
return false;
if (!is_numeral(to_app(t)->get_arg(0), c))
@ -454,6 +454,42 @@ bool poly_rewriter<Config>::is_mul(expr * t, numeral & c, expr * & pp) {
return true;
}
template<typename Config>
bool poly_rewriter<Config>::gcd_test(expr* lhs, expr* rhs) const {
numeral g(0), offset(0), c;
expr* t = nullptr;
unsigned sz = 0;
expr* const* args = get_monomials(lhs, sz);
auto test = [&](bool side, expr* e) {
if (is_numeral(e, c)) {
if (!c.is_int())
return false;
if (side)
offset += c;
else
offset -= c;
return true;
}
else if (is_mul(e, c, t)) {
if (!c.is_int() || c.is_zero())
return false;
g = gcd(abs(c), g);
return !g.is_one();
}
return false;
};
for (unsigned i = 0; i < sz; ++i)
if (!test(true, args[i]))
return true;
args = get_monomials(rhs, sz);
for (unsigned i = 0; i < sz; ++i)
if (!test(false, args[i]))
return true;
if (!offset.is_zero() && !g.is_zero() && !divides(g, offset))
return false;
return true;
}
template<typename Config>
bool poly_rewriter<Config>::mon_lt::operator()(expr* e1, expr * e2) const {