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2506.05541

THE COORDINATE FUNCTIONS OF THE HEIGHWAY DRAGON CURVE

D. A. Caprio

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

Audit review

The paper proves dim_B Xθ = dim_B Yθ = 1 − (log cos α)/(log 2) by explicit dyadic mesh counting: a uniform upper bound on oscillations in each dyadic column (Lemma 3.2) and a uniform lower bound via angle-combinatorics for rational α, then approximation for irrational α (Theorem 2.2), see the statement and proof outline in the text around Theorem 2.2 and Lemmas 3.2, 3.5, 3.6 . The candidate solution obtains the same formula using a de Rham-type functional equation for the complex parametrization and uniform oscillation bounds on dyadic intervals, then counts squares to get N_{2^{-n}} ~ (4r)^n and the same dimension. The two arguments are coherent but distinct: the paper avoids relying on an explicit self-similarity of the parametrization (remarking this property is not available in general beyond the Levy case) and instead uses careful covering/separation estimates, whereas the candidate’s proof leverages the exact two-map self-similarity of the limit curve and convex-hull width bounds. No contradiction was found; minor presentational clarifications would strengthen the paper but do not affect correctness.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The paper cleanly proves an exact box-counting dimension formula for the graphs of coordinate functions of generalized dragon curves. The argument balances explicit combinatorial control (rational angles) with a careful approximation step (irrational angles). The result is correct and of interest to the fractal geometry and dynamical systems communities working on self-similar curves. Some presentational refinements would further improve readability and rigor at a few technical junctures.