## Model Theory Seminar

Will Boney

Harvard

Nonelementary `compactness' through Ehrenfeucht-Mostowski models

**Abstract:**In 1999, Shelah proved that categoricity in a high successor in an Abstract Elementary Class with amalgamation implied a locality for Galois types over saturated models. The proof proceeded by an analysis of the Ehrenfeucht-Mostowski models of the class, which allowed for a compactnessish proof that witnesses to local equality could turned into witnesses to full equality. We revisit this technique and give some applications to other problems.

Tuesday December 5, 2017 at 1:00 PM in SEO 427