2412.05077
On Convergents of Proper Continued Fractions
Niels Langeveld, David Ralston
correctmedium confidence
- Category
- math.DS
- Journal tier
- Strong Field
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper’s Theorem 3.11 states exactly the sought equivalence for even candidates: p = p2, q = q2 occurs iff there exists a divisor a | p with Tp(x) + Ta(x) > 1; it proves this via a Beatty-sequence characterization and the identity q = ⌊p/x⌋ + 1 for even candidates . The candidate model independently proves the same equivalence by an explicit tail-parameterization t of the PCF, deriving formulas for T_{p2}(x) and T_{a1}(x) that force T_{p2}(x) + T_{a1}(x) > 1 in one direction and construct digits from a|p with t = (1−Tp)/Ta in the other. The two arguments are correct and substantively different in method: the paper uses Beatty sequences, while the model uses explicit algebra on the first two digits and tail. Key identities p2 = a1 b2 and q2 = b1 b2 + a2 used in both align with equation (10) in the paper , and the uniqueness of the even candidate denominator q = ⌊p/x⌋ + 1 matches Lemma 3.3 . The fractional-part map notation TN(x) = {N/x} is consistent across both .
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} strong field \textbf{Justification:} The main classification result for even second convergents (Theorem 3.11) is correct and neatly characterized by a simple inequality involving fractional parts. The argument is clear and leverages a Beatty-sequence viewpoint that complements the odd-index case. The exposition could benefit from a brief algebraic alternative (as in the model’s tail-parameter derivation) to illuminate the inequality, but the current proof is sound. Overall presentation and context are strong; only minor clarity improvements are suggested.