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2212.14212

KAM THEOREMS FOR MULTI-SCALE TORUS.

Weichao Qian, Yixian Gao, Yong Li

correctmedium confidence
Category
math.DS
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper proves a multi-scale KAM theorem for Hd(x,y,θ,η,ϕ,I) = Nd(y,η,I) + ε P(x/λ1, y, θ, η, λ2 ϕ, I) with λ1 = ε^α, λ2 = ε^β, giving: (1) persistence of invariant 3d-tori under (R), (2) partial frequency preservation under (K), and (3) isoenergetic tori preserving n frequency ratios under (R)+(K)+(Iso) with the stated β-bound; see Theorem 1.1 and Section 5 for the multiscale setup and iteration scheme . The model’s solution uses a canonical rescaling to convert weighted small divisors into a standard Diophantine condition on ρ(b) = (ω/λ1, Λ, λ2 Ω) and then runs a standard analytic a posteriori KAM/Newton scheme, also handling partial and isoenergetic constraints. This is mathematically equivalent in spirit to the paper’s weighted small-divisor formulation and homological equations (e.g., (5.8)), just presented in a different gauge with the same β restriction and the same three conclusions . Minor differences are present (e.g., the model states an explicit O(ε^σ) measure loss and “Whitney-analytic” dependence, while the paper asserts the relative measure tends to 0 and proves Whitney C^{d−1} regularity), but these do not constitute substantive conflicts with the main results .

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

Technically solid and consistent with established KAM schemes, the paper adapts Newton–KAM methods to a three-block multi-scale setting and proves persistence, partial preservation, and isoenergetic results. While many details follow standard lines, some technical estimates are deferred to references or sketched. Adding explicit quantitative measure bounds and clarifying the dependence of cutoffs on the slow scale would improve readability. Overall, the contribution is rigorous and useful to specialists.