English

A note on limsup sets of annuli

Number Theory 2025-02-17 v1 Dynamical Systems Metric Geometry

Abstract

We consider the set of points in infinitely many max-norm annuli centred at rational points in Rn\mathbb R^{n}. We give Jarn\'ik-Besicovitch type theorems for this set in terms of Hausdorff dimension. Interestingly, we find that if the outer radii are decreasing sufficiently slowly, dependent only on the dimension nn, and the thickness of the annuli is decreasing rapidly then the dimension of the set tends towards n1n-1. We also consider various other forms of annuli including rectangular annuli and quasi-annuli described by the difference between balls of two different norms. Our results are deduced through a novel combination of a version of Cassel's Scaling Lemma and a generalisation of the Mass Transference Principle, namely the Mass transference principle from rectangles to rectangles due to Wang and Wu (Math. Ann. 2021).

Keywords

Cite

@article{arxiv.2502.09807,
  title  = {A note on limsup sets of annuli},
  author = {Mumtaz Hussain and Benjamin Ward},
  journal= {arXiv preprint arXiv:2502.09807},
  year   = {2025}
}

Comments

12 pages

R2 v1 2026-06-28T21:43:53.677Z