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2111.06557

Mean Li–Yorke chaos and multifractal analysis on subshifts

Zijie Lin, Ercai Chen, Xiaoyao Zhou

correctmedium confidence
Category
Not specified
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper proves, for any irreducible one‑sided SFT (Σ_A, σ) and any ω∈Σ_A, that h_B(ML_ω)=0, h_P(ML_ω)=h(Σ_A), and h_B(LY_ω)=h(Σ_A). These are stated as Theorem 1.2 and Theorem 1.1, respectively, and are established via a general multifractal framework plus a bi‑Lipschitz transfer argument to pass from almost‑everywhere ω to every ω . The model’s results match the statements, but its proof contains key errors. In part (a), the central combinatorial step incorrectly deduces a small Hamming radius from a bound on the number of bad length‑ℓ windows; the correct direction yields |S|≤bℓ, not |S|≲b/ℓ, so the subsequent entropy estimate collapses. In parts (b)–(c), the construction relies on choosing free blocks whose first symbol differs from the corresponding symbol of ω, which is generally impossible for loops based at a fixed vertex in an SFT, and the periodic/aperiodic residue‑class issue is not handled. The paper’s proofs avoid these pitfalls by working in the generalized multifractal setting, using packing‑entropy tools and explicit bi‑Lipschitz maps ϕ_{ω,ω′} (and their block-structured versions ϕ^M_{ω,ω′}) to transfer results across base points and across cyclic components of Σ_A .

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The work gives precise quantitative results for the size of mean Li–Yorke and Li–Yorke partner sets for every base point in irreducible one‑sided SFTs, using a robust multifractal framework and a transfer method. The arguments are correct and contribute a clear picture of these chaotic sets in symbolic dynamics. Some light expository improvements would increase accessibility.