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2202.02066

Parabolic Carpets

Jonathan M. Fraser, Natalia Jurga

correctmedium confidence
Category
Not specified
Journal tier
Strong Field
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper proves that for almost quasi-Bernoulli measures on parabolic carpets, the L^q-spectrum equals the pressure root β(q) and dim_B F = dim_P F = β(0), via a δ-stopping antichain, one-rectangle L^q estimates tied to the 1D spectra of the coordinate projections, and an induced uniformly hyperbolic subsystem to control lower bounds through (almost) sub/super-multiplicativity of a singular value partition function. The candidate solution follows the same decomposition, introduces the same stopping-time antichain, derives the same per-rectangle estimate up to ε, and uses the same pressure/inducing mechanism to identify the critical exponent. Minor differences are expository (e.g., not separating the q ≤ 1 and q > 1 cases explicitly, and invoking the 1D spectrum as an assumption rather than citing the paper’s Theorem 4.1). Overall, the logical steps align closely with the paper’s argument and assumptions, and the conclusions match Theorem 6.1 and its corollaries. Key steps and definitions correspond directly to the paper’s S_δ stopping construction, Jensen/separation reduction, Φ_{s,q} partition sums, and the induced subsystem IN/I∞ argument for the lower bound, as stated in Sections 4–6 of the paper (e.g., Theorem 6.1 and Lemma 6.2).

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The paper establishes a precise L\^q-spectrum formula and dimension equalities for measures on parabolic carpets under natural, checkable assumptions. The method—balancing a per-rectangle reduction to 1D spectra with an induced uniformly hyperbolic subsystem and a carefully tailored pressure—is technically robust and clearly motivated. The contribution is substantial within the field of fractal geometry and non-conformal dynamics. Minor improvements to exposition (highlighting key case splits and parameter choices) would further enhance clarity.