Time: 12:30 – 13:30
Room: Wean Hall 8220
Speaker: Clinton Conley
Department of Mathematical Sciences
Title: Amenability and μ-hyperfiniteness
Abstract: Ornstein-Weiss showed in the early 80s that any measure-preserving Borel action of a countable amenable group on a standard probability space generates, after deleting a null set, a hyperfinite orbit equivalence relation. This was soon generalized by Connes-Feldman-Weiss to handle non-measure-preserving actions. After some background on amenability, we discuss a modern graph-theoretic approach to proving these theorems, building on work of Elek, Kaimanovich, and Kechris-Miller. This talk includes joint work with Gaboriau, Marks, and Tucker-Drob.