Hi John! On 24 Nov., 14:06, John Cremona <john.crem...@gmail.com> wrote: > This sounds reasonable to me. I know that in general we do not want > to try to coerce from Z/nZ to GF(n) for prime n since we do not want > to prove primality except deliberately. The reverse coercion is a > forgetful functor, so safe. But i nyour example, both GF(p) and Z/pZ > already exist, in which case it is surely good to coerce from the ring > to the field. > > Of course I may have missed a lot of the point of your suggestion...
No, that's exactly the point! My suggestion is about getting the pushout of the two matrix spaces right. The pushout is constructed using merging and concatenation (according to certain rules) of construction functors. The construction functors of GF(p) and of Integers(p) *know* whether they yield a field or not. So, primality is not tested. Now, I propose that two QuotientFunctors are merged so that the result yields a field if and only if one of the given functors yields a field. I just did so, in addition to changing another technical detail. And this seems to work. I guess it will be part of #8800, which is about pushout anyway and which is where I found the bug. Cheers, Simon -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
