2209.13952
Assouad-type Dimensions of Overlapping Self-affine Sets
Jonathan M. Fraser, Alex Rutar
correctmedium confidence
- Category
- Not specified
- Journal tier
- Strong Field
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper’s Theorem A (equations (1.2)–(1.3)) and its proof (Theorem 2.10) establish the exact Assouad-dimension formula for dominated rectangular self-affine sets, with a lower bound via carefully aligned weak tangents and a matching upper bound under the WSC, plus a slice/symbolic-fibre identification of suprema under WSC . The candidate solution replicates the headline statements but its proof contains serious errors: (i) it constructs a purported weak tangent π(K) × E′η by applying inverses to unions of full rectangles Un⊂K—yet Un⊂K is false; (ii) it asserts a general product rule dimA(A×B)=dimA A+dimA B, which the paper explicitly notes is false in general (only holds in the self-similar–times–compact setting) ; (iii) it claims Eη equals the geometric fibre Kxη for all η, whereas the paper only proves {xη}×Eη⊂K and equality of the suprema under WSC, not set equality in general ; and (iv) it assumes uniform fibre-covering constants without invoking the uniformity proposition (Proposition 2.6) that the paper develops for this purpose . Net: the paper’s argument is sound; the model’s is not.
Referee report (LaTeX)
\textbf{Recommendation:} no revision \textbf{Journal Tier:} strong field \textbf{Justification:} The paper gives sharp, conceptually clean Assouad-dimension and Assouad-spectrum formulas for overlapping dominated rectangular self-affine sets, under minimal projected separation. The methodology—aligned weak tangents, a self-similar product lower bound, and a uniform symbolic-fibre estimate—is technically solid and broadly applicable. The results improve understanding even under strong separation and resolve a known question about distinct Assouad vs. quasi-Assouad dimensions.