paper

AF -algebras from non AF groupoids

arXiv:2106.14032

Abstract

We construct ample groupoids from certain categories of paths, and prove that their -algebras coincide with the continued fraction AF algebras of Effros and Shen. The proof relies on recent classification results for simple nuclear -algebras. The groupoids are not principal. This provides examples of Cartan subalgebras in the continued fraction AF algebras that are isomorphic, but not conjugate, to the standard diagonal subalgebras.

version 4: final version, to appear in Transactions AMS; minor errors corrected

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