All times are Eastern Standard Time (EST).

The 2021 Category Theory Novemberfest will be held on the weekend of Friday, November 12th through Sunday, November 14th. The meeting will be virtual. (Links will be provided next week.) Following the tradition of past Octoberfests, this is intended to be an informal meeting, covering all areas of category theory and its applications.  Novemberfest will begin Friday, November 12th at 3:30 PM when Tom Leinster (U. Edinburgh) will give a talk to the UOttawa Math Department entitled “The mathematics of diversity”.

Abstract: What is the mathematical definition of diversity? Ecologists have debated how best to measure diversity for over 70 years, and the same question arises in multiple fields both in the life sciences and beyond. But it is only just now being appreciated that diversity is also a fertile source of new mathematics. It is closely related to entropy (already a core concept in subjects such as information theory), and indeed, sheds new light on this old concept. The story I will tell begins with category theory, passes through parts of geometry and analysis, and ends with an answer to the question: what is the canonical probability measure on a metric space?

Then contributed talks will begin Saturday morning at 9AM. Schedule, titles and abstracts are below. Contributed talks are 25 minutes + 5 minutes for questions. 

To attend the contributed talks on Saturday, November 13th and Sunday, November 14th, here is the link. It’s the same link both days. (If you have not used zoom before, the link will assist with download and install.  If you are shown a login page, please click the link again and it will login for you.)

 If you have any problems, contact Rick Blute at

Titles & Abstracts (updated)

Schedule (updated)

Video for Tom Leinster’s Novemberfest talk can be found here. The slides are here

Slides for Tom’s 2018 talk on Magnitude at the Azores Category Theory Conference can be found here.

Contributed Talks

David Spivak Slides

Aryan Ghobadi Slides

Marzieh Bayeh Slides

Joe Moeller Slides

Nicholas Meadows Slides

Cindy Lester Slides

Jonathan Weinberger Slides

Shayesteh Naeimabadi Slides

Toby Kenney Slides

Jason Parker Slides

Pablo Vazquez Slides

Susan Niefield Slides

Frederic Leblanc Slides

Ming Ng Slides

J.S. Lemay Slides

Christian Williams Slides