def test_semi_stable_frobenius_polynomial_t():
# an example where the frobenius polynomial depends on the purely ramified extension
# we make
x = polygen(QQ)
K = QQ.extension(x - 1, "one")
E = EllipticCurve(K, [49, 343])
assert E.discriminant() == -(2**4) * 31 * 7**6
assert E.j_invariant() == K(2**8 * 3**3) / 31
f1 = semi_stable_frobenius_polynomial(E, K * 7, 1)
f2 = semi_stable_frobenius_polynomial(E, K * 7, -1)(x=-x)
assert f1 == f2
