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2208.14830

FRACTAL DIMENSIONS OF THE MARKOV AND LAGRANGE SPECTRA NEAR 3

Harold Erazo, Rodolfo Gutiérrez-Romo, Carlos Gustavo Moreira, Sergio Romaña

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

Audit review

The uploaded paper proves the asymptotic d(3+Y) = 2·W(e^{c0}|log Y|)/|log Y| + O(log|log Y|/|log Y|^2) with c0 = −log log((3+√5)/2) for Y→0+ (Theorem 1.2), and also shows an optimality statement for reasonable approximations (Theorem 1.3) . The candidate solution derives the same leading term and error rate via a different route (thermodynamic formalism for a renewal-type Gauss–Cantor set). The main caveat is that the candidate attributes a global identity d(t)=min{1,2D(t)} to Moreira; the paper only relies on equality of truncated dimensions dim_H(L∩(−∞,t))=dim_H(M∩(−∞,t)) and then develops bespoke coverings/renormalizations near 3 . This overstatement does not affect the final asymptotic near 3, where 2D(t)<1. Net: both reach the same result; the proofs are substantively different.

Referee report (LaTeX)

\textbf{Recommendation:} no revision

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The paper delivers a sharp, explicit asymptotic for the Hausdorff dimension near the classical cusp t=3, together with an optimal error barrier for reasonable approximations. The approach—rooted in combinatorial renormalization of finite subwords and precise interval coverings—avoids heavier thermodynamic machinery while retaining full quantitative control. The exposition is structured and self-contained, and the constants are tracked to produce the Lambert W constant c0. This will be of strong interest to specialists in Diophantine approximation and the fractal geometry of spectra.