Time:  12:00  13:20 
Room: 
Doherty Hall 4303

Speaker: 
William Boney CMU 
Title: 
Model theory of L_{omega_1, omega}

Abstract:  L_{omega_1, omega} is the language we get when we start with L and allow for countable conjunctions and disjunctions. Among other things, this allows us to talk about things involving finiteness and countability and allows us to omit countable types with a sentence. However, we lose the Compactness Theorem and the Upward LowenheimSkolemTarski Theorem, our two favorite methods for constructing models. In this talk, we introduce L_{omega_1, omega} and some of the model construction methods that aim to replace these. 