The Joy of Abstraction book club

Run by Eugenia Cheng

in collaboration with the Topos Institute


Welcome to the The Joy of Abstraction book club! The Joy of Abstraction, by Eugenia Cheng, is an introduction to category theory for anyone who wants to get into the formality of the subject but does not necessarily have the mathematical background to read a standard textbook. Part 1 starts gently, so that readers can build up to the formality of rigorous mathematics even if they haven't encountered it before. Part 2 gets into formal rigorous category theory, including limits and colimits, duality, functors, natural transformations, and the Yoneda lemma.

Dr Cheng wanted to give people an opportunity to ask questions and get help with understanding the book. This book club was run asynchronously, at an approximate rate of one chapter per week and readers invited to submit questions for each chapter according to a published schedule. We then collated the questions and Dr Cheng made a video each week addressing the questions for that chapter. The questions were kept anonymous, and we welcomed any question that comes from you wanting to understand something more!

Dr Cheng maintains a webpage recording errata for The Joy of Abstraction here.

To create a sense of community, even amongst those who may not frequently have questions, we encourage anyone following along with this book club to add their name to our public list of participants using this form.


There is a YouTube playlist of all the videos so far, and you can subscribe to the Topos Institute YouTube channel to be notified of future uploads.

Chapter Question submission deadline Video
1 19th February
2 26th February
3 5th March
4 12th March
5 19th March
6 26th March
7 2nd April
8 9th April
9 16th April
10 23rd April
11 30th April
12 7th May
13 14th May
14 21st May
15 4th June
16 18th June
17 2nd July
18 16th July
19 30th July
20 13th August
21 27th August
22 10th September
23 24th September
24 + E 8th October


Website and video editing for this book club is provided by Tim Hosgood, and administrative support by Juliet Szatko.