16 Nov
2019
16 Nov
'19
12:44 p.m.
Dear Joseph In 2-categorical terminology, your A_f is the coinserter of the two functors X, Y : 1 --> A. Ross On 13 Nov 2019, at 5:04 AM, Joseph Collins <joseph.collins@strath.ac.uk<mailto:joseph.collins@strath.ac.uk>> wrote: Suppose that we have a category A. If we want to formally add a single morphism, say f:X -> Y, where X,Y are in A, but f is not in A, we can do the following: we look at the discrete category containing only X and Y - let us denote that as (X Y) - and the category with two objects and only a single morphism between them. Let's call this one (X -> Y). [For admin and other information see: http://www.mta.ca/~cat-dist/ ]