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Main Author: Punch, James
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.20544
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author Punch, James
author_facet Punch, James
contents Let $\mathbb{R}^m$ be endowed with the Euclidean metric. The covering radius of a lattice $Λ\subset \mathbb{R}^m$ is the least distance $r$ such that, given any point of $\mathbb{R}^m$, the distance from that point to $Λ$ is not more than $r$. Lattices can occur via the unit group of the ring of integers in an algebraic number field $\mathbb{K}$, by applying a logarithmic embedding $\mathbb{K}^*\rightarrow \mathbb{R}^m$. In this paper, we examine those lattices which arise from the cyclotomic number field $\mathbb{Q}(ζ_n)$, for a given positive integer $n\geq5$ such that $n\not \equiv 2\pmod{4}$. We then provide improvements to an upper bound in (de Araujo, 2024), and conclude with an upper bound on the covering radius for this lattice in terms of $n$ and the number of its distinct prime factors. In particular, we improve Lemma 2 of (de Araujo, 2024) and show that, asymptotically, it can be improved no further.
format Preprint
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institution arXiv
publishDate 2025
record_format arxiv
spellingShingle An improved upper bound on the covering radius of the logarithmic lattice of $\mathbb{Q}(ζ_n)$
Punch, James
Number Theory
11H31
Let $\mathbb{R}^m$ be endowed with the Euclidean metric. The covering radius of a lattice $Λ\subset \mathbb{R}^m$ is the least distance $r$ such that, given any point of $\mathbb{R}^m$, the distance from that point to $Λ$ is not more than $r$. Lattices can occur via the unit group of the ring of integers in an algebraic number field $\mathbb{K}$, by applying a logarithmic embedding $\mathbb{K}^*\rightarrow \mathbb{R}^m$. In this paper, we examine those lattices which arise from the cyclotomic number field $\mathbb{Q}(ζ_n)$, for a given positive integer $n\geq5$ such that $n\not \equiv 2\pmod{4}$. We then provide improvements to an upper bound in (de Araujo, 2024), and conclude with an upper bound on the covering radius for this lattice in terms of $n$ and the number of its distinct prime factors. In particular, we improve Lemma 2 of (de Araujo, 2024) and show that, asymptotically, it can be improved no further.
title An improved upper bound on the covering radius of the logarithmic lattice of $\mathbb{Q}(ζ_n)$
topic Number Theory
11H31
url https://arxiv.org/abs/2507.20544