I am underway, at last, with the project of improving and updating my notes on category theory. So, here are the first four chapters of Category Theory I: Notes towards a gentle introduction.
The ‘I’ in the new title signals that I am carving the old notes into Part I and Part II, and I am planning to work up Part I into a decent shape, while quite putting aside Part II for a good while. (Lichtenberg: “Just as certain writers, after first dealing their material a rough blow, say it naturally falls into two parts”.) And ‘Notes’ is a frank admission that the material still won’t be very smoothed out, and I’ll not be aiming for a polished book-style finish. ‘Gentle introduction’ means that it goes no doubt far too slowly for some.
I’d be really interested in comments on Chapter 3, which has given me a lot of grief.