Mathematical logic seminar - Mar 31 2020

Time: 3:30pm - 4:30 pm

Room: https://cmu.zoom.us/j/621951121

Speaker:     Ernest Schimmerling    
CMU

Title: Covering at limit cardinals of K

Abstract:

Theorem (Mitchell and Schimmerling, submitted for publication) Assume there is no transitive class model of ZFC with a Woodin cardinal. Let ν be a singular ordinal such that ν > ω2 and cf(ν) < | ν |. Suppose ν is a regular cardinal in K. Then ν is a measurable cardinal in K. Moreover, if cf(ν) > ω, then oK(ν) ≥ cf(ν).

I will say something intuitive and wildly incomplete but not misleading about the meaning of the theorem, how it is proved, and the history of results behind it.

Draft of the paper