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2010.14719

Packing topological entropy for amenable group actions

Dou Dou, Dongmei Zheng, Xiaomin Zhou

correctmedium confidence
Category
Not specified
Journal tier
Strong Field
Processed
Sep 28, 2025, 12:55 AM

Audit review

The paper proves the variational principle for amenable packing topological entropy by (i) a 5r-lemma-based argument showing h_Ptop(Z,{F_n}) ≥ sup_μ h^upper_loc_μ(Z,{F_n}) and (ii) a Joyce–Preiss/Feng–Huang style measure construction showing that for any s < h_Ptop(Z,{F_n}) there is a measure μ with h^upper_loc_μ(Z,{F_n}) ≥ s, hence sup_μ h^upper_loc_μ(Z,{F_n}) ≥ h_Ptop(Z,{F_n}). The candidate’s “lower bound” mirrors (ii), but their “upper bound” is flawed: it attempts to cover a μ-null leftover set N by countably many sets with zero packing pre-measure, a claim that is unjustified and generally false. Thus the model’s proof has a critical gap, while the paper’s proof is correct.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The paper rigorously establishes a natural and important variational principle for amenable packing topological entropy, extending classical results to the amenable-group setting. The techniques are appropriate and correctly executed. Minor revisions would improve readability and self-containment, especially in clarifying where assumptions are used and in briefly elaborating the measure construction adapted from prior work.