Martin Koerwien : The complexity of the isomorphism relation for countable models of omega-stable theories

Posted by David E. Marker , part of the Logic Seminar.

At

Sept. 20, 2007, 4 p.m.

In

SEO 427

Abstract

We compare two different notions of complexity: depth of a classifiable theory (in the sense of S. Shelah's Classification Theory) on the one hand side and Borel reducibility as defined by H. Friedman and L.Stanley on the other hand side. We show how these notions are related to the classification problem for classes of countable models of a theory and give some positive and negative results concerning their mutual relationship.