At long last, I have updated my notes Category Theory: A Gentle Introduction (now some x + 291 pages).
A good while ago, I received lists of corrections from a number of people, and just recently I’ve had another tranche of corrections, making over a hundred in all. Mostly these corrections noted typos. But there were also enough mislabelled diagrams, fumbled notation mid-proof, etc., to have no doubt caused some head-scratching. So I can only apologize for the delay in making the corrections.
I have also added a new early chapter and restored a couple of sections that were in a rather earlier version but got lost in the last one (thereby breaking some cross-references and no doubt producing more head-scratching).
These notes were originally written for my own satisfaction, trying to get some basics clear. But I know some people have found them useful (despite their very obvious shortcomings, unevenness, and half-finished character). So I hope some others will find the update helpful: you can download it from the category theory page here.