Hello, I am rereading Walters' book in particular the functor chapter. I am also reading Barr & Wells "Category Theory for Computing Science" (erd edition) ... in particular chapter 4 on diagrams, sketches, etc. In Walters' functor chapter, I am wondering whether Example 13 is totally correct. It doesn't seem to me that "A" is a graph and what is called a functor is really a graph morphism or to put it another way, Example 13 should be couched in terms of a (formal!!) diagram of shape "A". I know that somebody will respond and say that "A" is really a category with implicit identity arrows. However, my retort would be that "A" is intended to be a graph (without composition). What do others think? Regards, Bill Halchin 20-Sep-2001 19:27:30 -0300,1707;000000000000-00000019