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2404.04410

On the linearization of analytic diffeomorphisms of the torus

Fernando Argentieri, Livia Corsi

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

Audit review

The paper’s KAM proof hinges on anisotropic analytic domains and norms tailored to the weak-Bryuno construction, with a precise small-divisor estimate encoded by Φ(ℓ,β,δ) and the recursive radii δ_{β,n} and smoothing in β, culminating in Proposition 2 and Theorem 1.9; these are internally consistent and carefully supported by lemmas (e.g., Lemmas 3.10, 3.15–3.18) and the KAM step. The candidate’s argument, while close in spirit, incorrectly attempts to pass from the paper’s anisotropic linear estimate to an isotropic ℓ1-analytic norm bound for the cohomological solution u_n; the key inequality relating isotropic and anisotropic weights is reversed, breaking the claimed estimate ||u_n||_{δ_{n+1}} ≤ Γ_n ||w_n||_{δ_n}. It also omits the paper’s essential control of the inverse conjugacy term g_{n+1} and the slice-mapping mechanism needed under the weak-Bryuno condition.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The work establishes a genuinely weaker-than-Bryuno condition enabling a KAM linearization on higher-dimensional tori, with a new anisotropic framework and a complete KAM step. The arguments appear correct and well-structured; modest clarifications would enhance accessibility to readers not already familiar with anisotropic slice techniques.