Toby Bartels <t...@ugcs.caltech.edu> wrote:
>james dolan <jdo...@math.ucr.edu> wrote:
>>A "groupoid" is a category where all the morphisms are
>>invertible.  it may very well be interesting to generalize the
>>subject matter of this discussion to the case where c and d are
>>not necessarily groupoids, but to keep things simple for now i
>>won't do that in this post.
>You seem to agree with John Baez's classification,
>but he doesn't feel the need to limit to groupoids;
>perhaps a word on how you think that complicates things?
>Or is it just that groupoids are needed for the deep homotopy connection?