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2401.17765

Some questions concerning attractors for non-autonomous dynamical systems

Russell Johnson, Víctor Muñoz-Villarragut

correcthigh confidence
Category
math.DS
Journal tier
Strong Field
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper’s Theorem 3.11 states exactly the two claims: (1) any compact invariant set A whose points lie in the small (u,v)-block must be contained in M_ε, and (2) if A is a Lyapunov attractor relative to M_ε, then A is a Lyapunov attractor relative to Q×ℝ^d. The paper proves (1) immediately from Corollary 3.9, which asserts that any bi-infinite solution staying in the Δ-block lies on M_ε, and it sketches (2) by conjugating the dynamics on M_ε to a reduced local flow on Q×U and invoking Palmer’s Proposition 3 to lift Lyapunov attraction to the ambient phase space (Theorem 3.11 and its proof sketch; see and ). The candidate solution reaches the same conclusions by appealing to standard normally hyperbolic invariant manifold (NHIM) structure—local product neighborhood, strong-stable/unstable laminations, and local maximality—to get (1), and by saturating neighborhoods along strong-stable leaves to get (2). This is a different but sound route provided the usual NHIM hypotheses hold in the skew-product local-flow setting. Minor mismatches: the candidate adds a “projection condition” that is not part of the paper’s Lyapunov-attractor definition (Definition 2.1; ), and it assumes NHIM laminations/local maximality rather than using the paper’s explicit Corollary 3.9 lemma-based route (Lemma 3.8 and Corollary 3.9; , ). Overall, both are correct; the proofs are different.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The two-part Pliss reduction statement is correct and well-integrated into the paper’s skew-product framework. The proof of containment (1) is immediate from Corollary 3.9. The lifting of Lyapunov attraction (2) follows via a natural conjugacy to a reduced flow and an appeal to Palmer’s result. Minor improvements would be to make explicit the global-in-time existence of orbits that remain in the compact block (since the flow is only local) and to restate the precise assumptions of Palmer’s proposition to assure direct applicability.