# Karen Strung: Minimal dynamical systems, C*-algebras, and the classification program

C*-algebra seminar talk by Karen Strung (Prague)

Title: Minimal dynamical systems, C*-algebras, and the classification program

Abstract:

This talk is based on joint work with Robin Deeley and Ian Putnam, where we study the existence of minimal dynamical systems, their orbit and minimal orbit-breaking equivalence relations, and their applications to C*-algebras and K-theory. In particular, we show that given any finite CW-complex there exists a space with the same K-theory and cohomology that admits a minimal homeomorphism. The proof relies on the existence of homeomorphisms on point-like spaces constructed by the authors in previous work, together with existence results for skew product systems due to Glasner and Weiss.

To any minimal dynamical system one can associate minimal equivalence relations by breaking orbits at small subsets. These were originally used by Putnam in his study of Cantor minimal systems, in which case they are so-called AF relations. Using Renault's groupoid C*-algebra construction we can associate K-theory groups to minimal dynamical systems and orbit-breaking equivalence relations. We show that given arbitrary countable abelian groups G_0 and G_1 we can find a minimal orbit-breaking relation such that the K-theory of the associated C*-algebra is exactly this pair.

These results have important applications to the Elliott classification program for C*-algebras. In particular, we make a step towards determining the range of the Elliott invariant of the C*-algebras associated to minimal dynamical systems and their minimal orbit-breaking relations.

This will be a Zoom talk. Contact Sergey Neshveyev if you want to join.