- 11am: Meet on the first floor of SEO if you're already here. We will leave to lunch at 11:20.
- 11:30am: Lunch at Joy Yee's
- 1pm:
**One talk** - 2:30:
**Two talk** - 4pm:
**Three talk** - 5:30pm: Dinner at Jaks Tap

It is probably easiest to park in the university parking lot on Morgan St. between Roosevelt and Taylor.

Speaker: Lynn Scow

Title: Indiscernibles, EM-types, trees

Abstract: A generalized indiscernible is a set of parameters {a_i}_{i\subset I} in a model M indexed by an external structure I so that finite tuples from A have the same type in M, , provided the tuples of their indices have the same quantifier-free type in I. Generalized indiscernibles were introduced by Shelah in the 70's and have found a wide array of applications in classification theory. The EM-type of a generalized indiscernible is a means to encode the necessary first-order information in the indiscernible, and it can be a useful way to streamline compactness arguments. In this talk we will survey the uses of EM-types in working with generalized indiscernibles. As a consequence, we present a new Ramsey class of trees.

Speaker: Isaac Goldbring

Title: The fundamental group of a locally finite graph with ends: a hyperfinite approach

Abstract: It is well-known that the fundamental group of a finite, connected graph is a finitely generated free group, where one can take the chords of a spanning tree as a set of free generators. Diestel and Sprussel tried to give a similar combinatorial characterization of the end compactification of an infinite, locally finite, connected graph. They showed that the fundamental group embeds into a group of reduced words, where the words can have arbitrary countable order type and the notion of reduction is non-wellordered. Furthermore, they show that this group of reduced words embeds into an inverse limit of finitely generated free groups. In this talk, I will present a much simpler approach to this problem by showing how the fundamental group of the end compactification of a locally finite, connected graph embeds into the internal fundamental group of a hyperfinite (in the sense of nonstandard analysis) graph, which is then a hyperfinitely generated free group. I will discuss some applications of this result, including a simple proof that certain loops in the end compactification are non-nullhomologous. This is joint work with Alessandro Sisto.

Speaker: Maryanthe Malliaris

Title: Saturation of ultrapowers and the structure of unstable theories

Abstract: The talk will be about some very recent progress on Keisler's order, a far-reaching program of understanding basic model-theoretic structure through the lens of regular ultrapowers. I will explain Keisler's order and the perspective it gives on classifying the unstable theories, and discuss a recent paper of Malliaris and Shelah which applies model-theoretic techniques developed for the study of Keisler's order to solve a problem on cardinal invariants of the continuum.

Uri Andrews

Lynn Scow

April 5th, 2016

October 28th, 2014

October 22nd, 2013

April 18th, 2013

October 23rd, 2012

April 26th, 2012

October 11th, 2011

April 7th, 2011

October 26th, 2010