Kurt Gödel Research Center

2019 seminar talk: Preservation theorems for symmetric extensions and Krivine-style results

Talk held by Asaf Karagila (University of East Anglia, Norwich, UK) at the KGRC seminar on 2019-05-23.

Abstract

Jean-Louis Krivine has used methods of realizability to prove several new independence results in ZF+DC. We show how to obtain some of these results using classical methods.

For the proof we also need theorems which lets us preserve some bits of choice in symmetric extensions. One of these theorems is an old folklore result, and the other is a new theorem.