OpAlg seminar: Tim de Laat

Speaker: Tim de Laat (University of Münster)

Title: Obstructions to coarse embeddability of expanders into Banach spaces

Abstract: Expanders are sequences of finite sparse graphs with strong connectivity properties. It is well known that expanders do not coarsely embed into Hilbert spaces. However, the question whether there exists an expander that admits a coarse embedding into a uniformly convex space remains open. In this talk, I will explain how strengthenings of Kazhdans property (T) can be used to construct different types of expanders with bad embeddability properties.