2018
Dec
19

# Set Theory Seminar - Asaf Karagila (The Morris model)

2:00pm to 3:30pm

## Location:

Ross 63

Title: The Morris model
Abstract: Douglass Morris was a student of Keisler, and in 1970 he announced the
following result: It is consistent with ZF that for every \alpha, there is a set
A_\alpha which is the countable union of countable sets, and the power set of
A_\alpha can be partitioned into \aleph_\alpha non-empty sets.
The result was never published, and survived only in the form of a short
announcement and an exercise in Jech's "The Axiom of Choice". We go over the
proof of this theorem using modern tools, as well as some of its odd
implications about "size" and countability.