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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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6
src/ast/rewriter/poly_rewriter.h
View file

@ -65,7 +65,7 @@ protected:
void set_curr_sort(sort * s) { m_curr_sort = s; }
expr * const * get_monomials(expr * & t, unsigned & sz) {
expr * const * get_monomials(expr * & t, unsigned & sz) const {
if (is_add(t)) {
sz = to_app(t)->get_num_args();
return to_app(t)->get_args();
@ -86,7 +86,7 @@ protected:
bool hoist_multiplication(expr_ref& som);
expr* merge_muls(expr* x, expr* y);
bool is_mul(expr * t, numeral & c, expr * & pp);
bool is_mul(expr * t, numeral & c, expr * & pp) const;
class mon_lt {
poly_rewriter& rw;
@ -124,6 +124,8 @@ public:
bool is_var_plus_ground(expr * n, bool & inv, var * & v, expr_ref & t);
bool is_zero(expr* e) const;
bool gcd_test(expr* lhs, expr* rhs) const;
br_status mk_mul_core(unsigned num_args, expr * const * args, expr_ref & result) {
SASSERT(num_args > 0);

38
src/ast/rewriter/poly_rewriter_def.h
View file

@ -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 {

7
src/util/rational.h
View file

@ -387,8 +387,11 @@ public:
}
friend inline std::ostream & operator<<(std::ostream & target, rational const & r) {
target << m().to_string(r.m_val);
return target;
return target << m().to_string(r.m_val);
}
friend inline bool divides(rational const& a, rational const& b) {
return m().divides(a.to_mpq(), b.to_mpq());
}
friend inline rational gcd(rational const & r1, rational const & r2);