categories: RFC Walters "Categories and Computer Science"

[Galchin Vasili <vngalchin@yahoo.com>]

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