TRS: { rev(nil()) -> nil(), rev(++(x, y)) -> ++(rev1(x, y), rev2(x, y)), rev1(x, nil()) -> x, rev1(x, ++(y, z)) -> rev1(y, z), rev2(x, nil()) -> nil(), rev2(x, ++(y, z)) -> rev(++(x, rev(rev2(y, z))))} Fail