CARMA SEMINAR Speaker: Alexander Fish, School of Mathematics and Statistics, The University of Sydney Title: Product set phenomena for countable groups Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle Time and Date: 4:00 pm, Thu, 7th Nov 2013 Abstract: We analyse local combinatorial structure in product sets of two subsets of a countable group which are "large" with respect to certain classes (not necessarily invariant) means on the group. As an example of such phenomenon, we can mention the result by Bergelson, Furstenberg and Weiss which says that the sumset of two sets of positive density in integers contains locally an almost-periodic set. In this theorem, large sets are the sets of positive density, and a combinatorial structure is an almost periodic set. [Permanent link]