Fri Sep 22, 2006
60 Evans Hall, 4:10–6 PM
John Krueger (UC-Berkeley)
Some Results on Internal Approachability
An internally approachable set is a model which can be approximated by an increasing sequence of models, whose initial segments appear in the original model. This idea is basic to many combinatorial and forcing arguments in classical set theory. A related idea is that of an internally club set, which is a model which can be approximated by a sequence whose elements appear in the model. We will discuss the recent proof that these two notions are consistently distinct.