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2012.13234

STERNBERG THEOREMS FOR COUPLED MAP LATTICES

Ruben Berenguel, Ernest Fontich

correctmedium confidence
Category
math.DS
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:55 AM

Audit review

The paper proves a Sternberg-type linearization for coupled map lattices with spatial decay by (i) constructing a finite-order normal form using Γ-spectrum/Sylvester-operator arguments and (ii) completing the conjugacy via a contraction mapping on an iterated/rescaled map F^m (operator G_m) under quantitative gap conditions derived from α, β and r0; see Theorem 1, Lemma 3 and the contraction estimate (17) as well as the normal-form step in Section 7 (Theorem 6) . The candidate’s solution also achieves linearization in the same setting but via a different proof: it solves the homogeneous cohomological equations up to order r0 using an explicit Neumann-series right inverse for L_M (enabled by α′>(β′)^s) and then solves the full conjugacy by a direct contraction on a weighted C^r_Γ space of maps vanishing to order r0+1. Both approaches rely on the Banach-algebra structure of L_Γ and smallness of B to ensure M, M^{-1} ∈ L_Γ (Proposition 3 and Proposition 4) . The assumptions align with the paper’s (H1)–(H2), and the model’s stronger modulus gap α′>(β′)^s implies the finite non-resonance used in the paper. Hence both are correct, but the proofs differ in the way the homological equations are solved and how the final contraction is set up.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The manuscript correctly extends Sternberg linearization/normal-form ideas to coupled map lattices endowed with decay, using a well-developed \$\Gamma\$-spectrum framework. The proofs are careful and quantitative, relying on precise Banach-algebra and spectral estimates. The contribution is specialized but valuable for the analysis of spatially extended discrete-time systems. Minor clarifications would improve readability and highlight the relation to classical approaches and to alternative fixed-point implementations.