arXiv:2306.00847v2
Abstract
Kurzweil's theorem ('55) is concerned with zero-one laws for well approximable targets in inhomogeneous Diophantine approximation under the badly approximable assumption. In this article, we prove the divergent part of a Kurzweil type theorem via a suitable construction of ubiquitous systems when the badly approximable assumption is relaxed. Moreover, we also discuss some counterparts of Kurzweil's theorem.
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Detailed mathematical audit
01Statements3 reported findingsCorrect
The Hausdorff-measure Kurzweil theorem, its badly approximable consequences, and the sufficient condition for full measure are correct, with one harmless range correction in an auxiliary proposition.
The Hausdorff zero-full criterion is correct
Pages 2 and 5–9 · Theorem 1.3 · arXiv:2306.00847v2
The convergence half follows from Hausdorff–Cantelli on the return balls. For divergence, the best-approximation scales define a locally ubiquitous system with the announced radius; the ubiquity theorem converts divergence of the same series into full Hausdorff measure.
Full paper, version 2 ↗The parameter must satisfy
Page 9 · Proposition 5.1 · arXiv:2306.00847v2
The proposition is printed for every but concludes inclusion in , while was defined only for . Its proof yields the positive lower bound precisely when , and Theorem 1.7 applies it only with . Replace the proposition’s range by ; no downstream statement changes.
The full-measure criterion follows from the best-approximation sequence
Pages 4 and 9–10 · Theorem 1.7 · arXiv:2306.00847v2
The summability hypothesis makes the exceptional events summable. Borel–Cantelli places almost every target in the eventual lower-bound set, and Proposition 5.1 with gives membership in .
02Proofs2 reported findingsCorrect
The Hausdorff–Cantelli, ubiquity, transference, and Borel–Cantelli arguments are correct and complete in their operative ranges.
The convergence and divergence proofs use the same scale sequence
Pages 5–9 · Sections 3–4 · arXiv:2306.00847v2
The selected return times have a uniform contraction ratio, the resonant balls cover a fixed proportion at each scale, and the series in the ubiquity theorem is exactly the one in Theorem 1.3 up to fixed constants.
The sufficient-condition proof closes
Pages 9–10 · Section 5 · arXiv:2306.00847v2
The intervals cover every sufficiently large denominator scale, and the transference inequality gives the required lower bound after the range correction . The summability assumption then supplies the almost-everywhere conclusion.
03Novelty0 reported findingsNo non-novelty findings
No non-novelty findings.