Entropy Density of Uniquely Ergodic Measures for Full Shifts over Amenable Residually Finite Groups

Abstract

We study entropy density for full shifts over amenable residually finite groups. Entropy density means that every invariant measure can be approximated in the weak$^*$ topology, together with its entropy, by measures from a distinguished family. In symbolic dynamics it is known, by a result of Weiss, that uniquely ergodic measures are entropy dense among ergodic measures for the shift action of $\mathbb Z$. We extend this result to full shifts over amenable residually finite groups: invariant measures supported on uniquely ergodic subsystems are entropy dense in the collection of ergodic invariant measures. This applies in particular to full shifts over finitely generated abelian groups. The proof uses Cortez--Petite Følner tilings and a block-replacement construction adapted to finite-index subgroups.

Disclosure

“owledgements The authors are grateful to Dominik Kwietniak for many valuable suggestions and remarks. MM was supported by the National Science Centre (NCN), Poland, grant no. 2022/47/B/ST1/02866. Use of AI-assisted tools AI-assisted tools were used to support language editing, proofreading, and im- proving the clarity of exposition. AI-assisted tools were also used in discussions of the presentation of selected proofs. The authors reviewed and ver”

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2026-08-23T18:58:07.539989Z

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