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 ...

People in measure theory find it best to work with, not arbitrary measurable spaces, but certain nice ones called standard Borel spaces. I’ve used them myself. a finite or countably infinite set with ...

Earlier this month the Mathematics Institute at Uppsala University hosted a conference called Categorification in Algebra and Topology, clearly a theme close to our collective heart. As yet there are ...

Feb 2, 2025 If you want to help save US federal web pages and databases, here are some things to do.

I hope you’ve read the news: Ethan Singer, Thousands of U.S. government web pages have been taken down since Friday, New York Times, 2 Feburary 2025. Many of the pages taken down mention DEI, but they ...

Last time, I talked about the magnitude of a set-valued functor. Today, I’ll introduce the comagnitude of a set-valued functor. I don’t know how much there is to the comagnitude idea. Let’s see! I’ll ...

Jan 22, 2025 Warming up to a dual concept to magnitude, with an aside on a new connection between magnitude and entropy.

In this post and the next, I want to try out a new idea and see where it leads. It goes back to where magnitude began, which was the desire to unify elementary counting formulas like the ...

We’re brought up to say that the dual concept of injection is surjection, and of course there’s a perfectly good reason for this. The monics in the category of sets are the injections, the epics are ...

Jan 16, 2025 19:51 Ah, now that’s a very interesting point. Someone who’s fluent in dagger categories would probably have further thoughts about that.

Jan 11, 2013 An extension of the monadicity theorem using F-categories to detect lax, pseudo, and colax morphisms provides new insight into the fundamental nature of such weak morphisms. Cobordism and ...