## Characteristic factors for commuting actions of amenable groups

### Time

Feb 21 2013 – 3:00pm – 4:00 pm

### Location

MW154

### Speaker

Donald Robertson (Ohio State University)

### Abstract

A coarse description of sub-sigma-algebras that characterize the behavior of averages arising from commuting actions of an amenable group will be given. The averages generalize those used in the ergodic proof of Szemeredi’s theorem. The description will be used to prove an ergodic version of Roth’s theorem for amenable groups.