8 Sep
2002
8 Sep
'02
2:33 p.m.
That should have been "up to equivalence." I was forgetting that g and k need not be monic. Vaughan Pratt
Associate to each (C,g,k) the full subcategories \G, \K of C having as objects those of im(g), im(k) respectively, together with a GxK matrix Q of cardinals giving the cardinality |C(g(i),k(j))| for i,j in G,K. These associated entities are all preserved up to isomorphism by GK-functors. ^^^^^^^^^^^^^^^^^