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2210.07941

Topological synchronisation or a simple attractor?

Théophile Caby, Michele Gianfelice, Benoît Saussol, Sandro Vaienti

correctmedium confidence
Category
math.DS
Journal tier
Note/Short/Other
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper proves that for Collet–Eckmann S‑unimodal maps with a quadratic critical point and slow recurrence, the acip’s generalized dimensions satisfy D_q = 1 for q < 2 and D_q = q/(2(q−1)) for q ≥ 2, relying on a density decomposition with square‑root cusps and a Legendre‑transform characterization of D_q; see Proposition 5.1 and the density form h(x)=ψ0(x)+∑k≥1 φk(x)/√|x−z_k| with exponentially decaying amplitudes. The candidate model derives the same spectrum by directly estimating I_q(r)=∫μ(B(x,r))^{q−1} dμ(x), splitting contributions from regular regions and cusp neighborhoods. The conclusions match, with the model offering a more direct integral computation and the paper using a multifractal-formalism route. Minor differences are present (e.g., the model should weight cusp neighborhoods by decaying amplitudes), but they do not affect the final result. Overall, both are correct and essentially consistent in assumptions and outcome.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} note/short/other

\textbf{Justification:}

The paper concisely derives the generalized-dimensions spectrum for a standard class of unimodal maps under familiar nonuniform hyperbolicity assumptions. The result is correct and sheds light on numerical observations (zipper effect). Minor clarifications would strengthen rigor—chiefly, explicitly reconciling the correlation-integral definition with the Legendre-transform characterization in the specific two-exponent setting and making the role of cusp amplitudes fully explicit.