Kurt Gödel Research Center

2014 seminar talk: Cancelled: Survey on the Tukey theory of ultrafilters

Talk held by Natasha Dobrinen (University of Denver, Colorado, USA) at the KGRC seminar on 2014-01-07.

Abstract

This talk has been cancelled (due to a flight cancellation).

The Tukey order on ultrafilters is a weakening of the well-studied Rudin-Keisler order, and the exact relationship between them is a question of interest. In a second vein, Isbell showed that there is a maximum Tukey type among ultrafilters and asked whether there are others. These two questions are the main guiding forces of the current research. In this talk, we present highlights of recent work of Blass, Dobrinen, Mijares, Milovich, Raghavan, Todorcevic, and Trujillo (in various combinations for various papers). Further information about results mentioned in this talk can be found in a recent survey article by the speaker.