Hi Volker, On 15 Sep., 11:45, Volker Braun <vbraun.n...@gmail.com> wrote: > b in QQ is (or should be) equivalent to QQ(b) not throwing an error.
No, that's incorrect. It should be (and is) equivalent to QQ(b)==b returning True. QQ(b) is just a conversion. You can convert any element of a finite prime field into QQ: sage: b = GF(5)(2) sage: QQ(b) 2 However, the test "QQ(b)==b" is not only testing whether conversion works, but also whether there is a coercion from the ring containing b to QQ. In my example, there is no coercion, thus, no equality: sage: cm.explain(QQ, b.parent()) Will try _r_action and _l_action Unknown result parent. sage: QQ(b) == b False Hence, we have sage: b in QQ False Best regards, Simon -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
