## EVENT DETAILS AND ABSTRACT

**Dynamical Systems Seminar**
**Title:** Sumsets with one dense summand

**Speaker:** John Griesmer

**Speaker Info:** Ohio state University

**Brief Description:**

**Special Note**:

**Abstract:**

When A and B are subsets of an abelian group, the sumset A+B := {a+b| a in A, b in B} tends to be highly structured. A classical example is the Steinhaus lemma, which says that when A and B are sets of reals having positive Lebesgue measure, then A+B contains an interval. We will survey some analogous results for sets of integers and see a strong connection to ergodic theory. This will lead to some classical and (perhaps) new questions about recurrence and ergodic averages.

**Date:** Tuesday, February 07, 2012

**Time:** 4:00PM

**Where:** Lunt 105

**Contact Person:** Prof. Bryna Kra

**Contact email:** kra@math.northwestern.edu

**Contact Phone:** 847-491-5567

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