Formulating kappa-complete ultrafilters in category theory

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.