Amenable wreath products with non almost finite actions of mean dimension zero

Abstract

Almost finiteness was introduced in the seminal work of Kerr as an dynamical analogue of Z-stability in the Toms-Winter conjecture. In this article, we provide the first examples of minimal, topologically free actions of amenable groups that have mean dimension zero but are not almost finite. More precisely, we prove that there exists an infinite family of amenable wreath products that admit topologically free, minimal profinite actions on the Cantor space which fail to be almost finite. Furthermore, these actions have dynamical comparison. This intriguing new phenomenon shows that Kerr's dynamical analogue of Toms-Winter conjecture fails for minimal, topologically free actions of amenable groups. The notion of allosteric group holds a significant position in our study. A group is allosteric if it admits a minimal action on a compact space with an invariant ergodic probability measure that is topologically free but not essentially free. We study allostery of wreath products and provide the first examples of allosteric amenable groups.

arXiv comment16 pages. Final version, to appear in Trans. Amer. Math. Soc

References in corpus (8)

• Nuclear dimension of simple C*-algebras
• The C*-algebra of a minimal homeomorphism of zero mean dimension
• Stability and Invariant Random Subgroups
• Folner tilings for actions of amenable groups
• Minimal Dynamics and K-theoretic Rigidity: Elliott's Conjecture
• Stabilizers of Actions of Lattices in Products of Groups
• Continuum of allosteric actions for non-amenable surface groups
• Classifiability of crossed products by nonamenable groups