# Formulating kappa-complete ultrafilters in category theory

**Date**: Wednesday 12 December 2018, 14:00 – 15:00**Location**: Mathematics Level 8, MALL 1, School of Mathematics**Type**: Proofs, Constructions and Computations, Seminars, Pure Mathematics**Cost**: Free

#### Andrew Brooke-Taylor, University of Leeds. Part of the proofs, constructions and computations seminar series.

An old theorem of Isbell shows how one can formulate the measurability of a cardinal in category-theoretic terms. After presenting Isbell's result, I will discuss some more recent ideas (from joint work with Joan Bagaria and Jiri Rosicky) about formulating normality of an ultrafilter in a similar way.