Minimal dynamics and Z-stable classification

Abstract

Let X be an infinite compact metric space, α: X \to X a minimal homeomorphism, u the unitary implementing αin the transformation group C*-algebra, and S a class of separable nuclear C*-algebras that contains all unital hereditary C*-subalgebras of C*-algebras in S. Motivated by the success of tracial approximation by finite dimensional C*-algebras as an abstract characterization of classifiable C*-algebras and the idea that classification results for C*-algebras tensored with UHF algebras can be used to derive classification results up to tensoring with the Jiang-Su algebra Z, we prove that the transformation group C*-algebra tensored with a UHF algebra is tracially approximately S if there exists a y in X such that a certain C*-subalgebra is tracially approximately S. If the class S consists of finite dimensional C*-algebras, this can be used to deduce classification up to tensoring with Z for C*-algebras associated to minimal dynamical systems where projections separate tracial states. This is done without making any assumptions on the real rank or stable rank of either the transformation group C*-algebra or the C*-subalgebra, nor on the dimension of X. The result is a key step in the classification of C*-algebras associated to uniquely ergodic minimal dynamical systems by their ordered K-groups. It also sets the stage to provide further classification results for those C*-algebras of minimal dynamical systems where projections do not necessarily separate traces.