6 Oct
2016
6 Oct
'16
9:15 a.m.
How about two objects A and B, with hom(A,A)=hom(B,B) the natural numbers, and hom(A,B)=hom(B,A) the positive integers, and all compositions given by addition? Steve.
On 5 Oct 2016, at 5:21 AM, Michael Barr <barr@math.mcgill.ca> wrote:
We all know that if Hom(A,-) is naturally equivalent to Hom(B,-), then A is isomorphic to B. But can you find a category in which for each object C, Hom(A,C) is isomorphic to Hom(B,C) but no naturality of the isomorphism without A being isomorphic to B?
Michael
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