I want to go back over something from Part 11, but in a more systematic and self-contained way. I’m stating these facts roughly now, to not get bogged down. But I’ll state them precisely, prove them, ...

As a digression from our usual fare on the n n -Café, here’s one of my favorites, about an early theory of the Solar System, ...

The Eighth International Conference on Applied Category Theory (https://easychair.org/cfp/ACT2025) will take place at the University of Florida on June 2-6, 2025. The ...

Dec 15, 2024 More detail on the Cycle Length Lemma, a basic result in the theory of random permutations. We prove a categorified version of this result, which is an equivalence of groupoids, and then ...

This is the homepage for the UT Geometry and Quantum Field Theory Seminar. At the organizational meeting we will flesh out the details of our plans for the semester. Below are some suggestions to get ...

Nov 1, 2022 John Baez is giving a talk on categories and epidemiology on Wednesday November 2nd, viewale online at noon UTC. A Categorical Understanding of the Proof of Cantor-Schröder-Bernstein? Dec ...