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
- arXiv Links
- Abstract ↗PDF ↗
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.