‘But pardon, and gentles all’

November was a busy month. A wonderful week out in Vienna (not to mention the time out before and after, getting ready and recovering from the excitements!). Peter Johnstone’s tough category theory lectures to keep on top of. Reading for the 2016 version of the Teach Yourself Logic guide to be done.

The Gentle Introduction to matters categorial has, therefore, not got anywhere near as much attention as I would have liked. Pardon, gentles all.

I have, however, uploaded a new version — now 171 pages, with two short new chapters (one either side of the chapter on exponentials). Prompted by Paolo Giarrusso, I’ve completely recast what was a short and potentially misleading section on subobjects into a standalone chapter. And I’ve added another chapter on some mathematical gadgets to be found inside categories, namely group objects and natural number objects (though as you’ll see the current version ducks out of giving a clean proof of the final stated theorem on recursion). I have also tinkered elsewhere with the first dozen chapters — the ones preceding the introduction of functors — at quite a few scattered points, not least in sorting some typos. The later chapters from functors onwards, by contrast, remain untouched.  As I say, not the state that I’d like the Gentle Introduction to have got to. But I won’t have much time to look at it again over the next few weeks (for various nice reasons), so I thought I should at least make available such improvements as I have been able to make. Here, then, is the latest version.

So please do continue to “piece out our imperfections with your thoughts” and let me know of corrections, obscurities, possible improvements etc.

And “your humble patience pray/Gently to hear, kindly to judge” these efforts so far!