There is now, at last, a full draft of *Introducing Category Theory*. You can download the PDF here.

The second half still needs more proof-reading and needs indexing. But I don’t envisage adding significantly to the content. After all — rather crazily for a book I didn’t originally set out to write — it is already 450 large format, small print, pages. Which is surely enough for an elementary, limited-ambition, introduction.

I hope, as a certain author once put it, it will provide interested readers with a ladder they can throw away after they have climbed up it, now primed to tackle some of the standard books by real category theorists. (Though, unlike that author, I certainly don’t intend that “anyone who understands me eventually recognizes [what I wrote] as nonsensical.”! Any nonsensical bits are plain mistakes.)

What’s the plan from here on? I want to complete the indexing pretty speedily, and do another proof-reading for the second half (though I seem to be increasingly bad at that!). And then I’m minded to promptly paperback it, though as a frankly acknowledged “beta version” with the expectation that I’ll certainly need to update it to correct typos and thinkos. But many readers will *much* prefer to work at least in part from a printed copy.

(I would have quite liked to have modest colour printing for some of the diagrams, to set off panels for theorems, etc. but that would more than double the book cost. The zero-royalties price for black-and-white Amazon print-on-demand, as with the other Big Red Logic Books, should be a tolerable £10.75, $14.90, €13.75 — still just the price of a few coffees.)

Rowsety MoidGood progress! (My plan is to try to read it properly once it’s available on paper.)

A question: At the end of the preface, it says “The last chapter of Part II is still being revised/expanded and is not included in this version.” Is that correct? I don’t see an obvious gap there. The current Chapter 27, ‘Toposes as classical arenas’, looks like a suitable last chapter for that part.

Peter SmithI forgot to amend the box at the end of the Preface!

Karo MaestroCongratulations! I think the definitive introduction to category theory for mathematicians that currently exists is Emily Riehl’s remarkable book, which I had the joy of reviewing at my blog when it first came out. I still think it should be mandatory reading for graduate students in the philosophy of mathematics. It’s so wonderful you’ve written this book for the latter group of students and experts-and it can make wonderful supplementary reading for mathematicians working through Riehl.

Yuiang ZhouCongratulations! Can’t wait to see the print version.