A Gelfand-type duality for coarse metric spaces with property A

TL;DR

This paper establishes a duality between automorphisms of Roe algebras and coarse equivalences of metric spaces with property A, revealing deep connections between algebraic and geometric structures.

Contribution

It proves isomorphisms between automorphism groups of Roe algebras and coarse equivalence groups for spaces with property A, extending Gelfand duality concepts.

Findings

Outer automorphisms of uniform Roe algebras correspond to coarse automorphisms.

Outer automorphisms of Roe algebras correspond to coarse automorphisms.

Uniform approximability results for maps between Roe algebras.

Abstract

We prove the following two results for a given uniformly locally finite metric space with Yu's property A: 1) The group of outer automorphisms of its uniform Roe algebra is isomorphic to its group of bijective coarse equivalences modulo closeness. 2) The group of outer automorphisms of its Roe algebra is isomorphic to its group of coarse equivalences modulo closeness. The main difficulty lies in the latter. To prove that, we obtain several uniform approximability results for maps between Roe algebras and use them to obtain a theorem about the `uniqueness' of Cartan masas of Roe algebras. We finish the paper with several applications of the results above to concrete metric spaces.