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2405.10179

Conditions on the continuity of the Hausdorff measure

Rafał Tryniecki

correcthigh confidence
Category
Not specified
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper proves that for the linear IFS generated by the partition points b_k (with inverse branches g_k mapping [0,1] to [b_k,b_{k-1}]), if (1−h_n) ln n → 0 and sup_k (b_k−b_{k+1})/b_{k+1} < ∞, then H^{h_n}(J_n) → 1; it sets up OSC, the dimension equation ∑(b_k−b_{k+1})^{h_n}=1, an upper bound H^{h_n}(J_n) ≤ 1 via cylinder covers, and a delicate lower bound via density theorems and Lemma 4.1 (which requires condition (2)), culminating in Theorem 4.8. These steps are explicitly laid out and coherent in the manuscript . The model presents a shorter approach based on a self-similar (h_n-conformal) measure and a Frostman-type estimate, and claims condition (2) is unnecessary. However, its key estimate incorrectly bounds the number of (m−1)-level “parents” intersecting a given interval by n+2; there can be arbitrarily many tiny parents inside the interval. This gap prevents the claimed uniform Frostman inequality as written. The argument can be repaired by replacing the faulty counting step with the inequality a^h ≤ δ^{h−1} a for a ≤ δ (taking δ = |I|/n), yielding μ_n(I) ≤ n^{1−h_n}(1+2/n)|I|^{h_n} and the same limit under (1). But because this fix is not in the submitted solution, the model’s proof is formally flawed. The paper’s proof, using both (1) and (2), is correct as written.

Referee report (LaTeX)

\textbf{Recommendation:} reject

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The paper’s main theorem is proved correctly under clearly stated hypotheses, combining an easy upper bound with a careful density-based lower bound. The structure is sound and the examples verify the key asymptotic condition. The competing model solution contains a substantive flaw in its Frostman estimate and cannot be accepted without a repair; although a small fix is available, it is absent from the submitted solution. The paper stands as correct as written, even if a shorter alternative approach likely exists.