Another update to Category Theory: Notes towards a gentle introduction. This time, I have rewritten and indeed doubled the length of the chapter on subobjects and subobject classifiers. Much improved, I hope! I’ve also added two or three needed results at the appropriate places earlier in the notes, so that the proofs in this newly revised chapter can be snappy, and corrected some random typos I happened to notice.
(I’ll be pausing on categories now for a few weeks, with a holiday break coming up.)