2508.13501
An infinite-dimensional Kolmogorov theorem and the construction of almost periodic breathers
Zhicheng Tong, Yong Li
correctmedium confidence
- Category
- math.DS
- Journal tier
- Strong Field
- Processed
- Sep 28, 2025, 12:57 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper’s Theorem 2.1 establishes a Kolmogorov-type result on the thickened infinite torus T∞_σ under Bourgain’s Diophantine nonresonance, using a generating-function-based KAM scheme with a carefully designed contraction sequence and super-exponential convergence. It proves the existence of an exact symplectic triangular map x = u(ξ), y = v(ξ) + ⟨u_ξ(ξ)^{-1}, κ⟩ mapping D_{σ/4,σ/4} into D_{σ,σ}, with W_ξ(ξ,0) = 0 and W_κ(ξ,0) = ω, and obtains quantitative bounds of order O(1/K) (specifically, ∥ϕ−id∥ ≤ 2 σ^{2/η}/K and ∥W_{κκ}−Q∥ ≤ 2 σ^{2/η−1}/K). The candidate solution instead proposes a Newton–KAM parameterization scheme with fixed analyticity loss, claims convergence after only three steps while also asserting exact satisfaction of the Kolmogorov conditions, and derives bounds of order O(e^{-K})—all of which conflict with the paper’s precise iteration design and final quantitative estimates. Furthermore, the candidate’s stepwise triangular resolution (e.g., setting h = 0 when solving for the constant part k̄) is not justified, and the domain-loss accounting is inconsistent with the need for infinitely many KAM steps to reach exact conjugacy.
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} strong field \textbf{Justification:} The paper introduces an infinite-dimensional Kolmogorov theorem with frequency preservation under Bourgain’s Diophantine nonresonance and extends it to a weak Diophantine regime, with a noteworthy application to almost periodic breathers. The approach is conceptually clear, technically robust, and provides explicit quantitative estimates. Minor expository adjustments would further improve readability and self-containment.