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 conference will be preceded by ...

Previously: Part 8. Next: Part 10. It’s the penultimate week of the course, and up until now we’ve abstained from using the axiom of choice. But this week we gorged on it. The section I most enjoyed ...

for all infinite sets X X and Y Y. Proving this required most of the concepts and results from the second half of the course: well ordered sets, the Cantor–Bernstein theorem, the Hartogs theorem, Zorn ...

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 ...