EVENT DETAILS AND ABSTRACT

Title: Discrete analogues of characteristic factors
Speaker: Julia Wolf
Speaker Info: Ecole Polytechnique
Brief Description:
Special Note:
Abstract:

The notion of a characteristic factor for a given ergodic average was already implicit in Furstenberg's proof of Szemeredi's theorem but has come to play a central and more explicit role in recent years. For example, Host and Kra showed how characteristic factors naturally arise from a family of (semi-)norms. These have an obvious analogue in the so-called uniformity or U^k norms introduced by Gowers in the discrete context. We survey some of the approaches to "discrete characteristic factors" that have been developed to give quantitative answers to certain number-theoretic questions, including joint work with Tim Gowers.