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Related papers: Hausdorff dimensions in $p$-adic analytic groups

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We establish that finitely generated non-abelian direct products $G$ of free pro-$p$ groups have full Hausdorff spectrum with respect to the lower $p$-series $\mathcal{L}$. This complements similar results with respect to other standard…

Group Theory · Mathematics 2025-05-23 Iker de las Heras , Benjamin Klopsch , Anitha Thillaisundaram

Using wreath products, we construct a finitely generated pro-p group G with infinite normal Hausdorff spectrum with respect to the p-power series. More precisely, we show that this normal Hausdorff spectrum contains an infinite interval;…

Group Theory · Mathematics 2020-01-08 Benjamin Klopsch , Anitha Thillaisundaram

Recently the first example of a family of pro-$p$ groups, for $p$ a prime, with full normal Hausdorff spectrum was constructed. In this paper we further investigate this family by computing their finitely generated Hausdorff spectrum with…

Group Theory · Mathematics 2021-06-25 Iker de las Heras , Anitha Thillaisundaram

Let $G$ be a $p$-adic analytic pro-$p$ group of dimension $d$. We produce an approximate series which descends regularly in strata and whose terms deviate from the lower $p$-series in a uniformly bounded way. This brings to light a new set…

Group Theory · Mathematics 2025-09-11 Iker de las Heras , Benjamin Klopsch , Anitha Thillaisundaram

For each odd prime $p$, we produce a $2$-generated pro-$p$ group $G$ whose normal Hausdorff spectra \[ \mathrm{hspec}_{\trianglelefteq}^{\mathcal{S}}(G) = \{ \mathrm{hdim}_{G}^{\mathcal{S}}(H)\mid H\trianglelefteq_\mathrm{c} G \} \] with…

Group Theory · Mathematics 2020-05-05 Iker de las Heras , Benjamin Klopsch

Let $G$ be a finitely generated pro-$p$ group of positive rank gradient. Motivated by the study of Hausdorff dimension, we show that finitely generated closed subgroups $H$ of infinite index in $G$ never contain any infinite subgroups $K$…

Group Theory · Mathematics 2024-08-28 Oihana Garaialde Ocaña , Alejandra Garrido , Benjamin Klopsch

We study the Hausdorff dimension of R-analytic subgroups in an R-analytic profinite group, where R is a pro-p ring whose asso- ciated graded ring is an integral domain. In particular, we prove that the set of such Hausdorff dimensions is a…

Group Theory · Mathematics 2016-05-25 Gustavo A. Fernández-Alcober , Eugenio Giannelli , Jon González-Sánchez

Klopsch and the author have constructed a finitely generated pro-p group G, for p an odd prime, with infinite normal Hausdorff spectrum with respect to the p-power series. They show that the normal Hausdorff spectrum of G contains an…

Group Theory · Mathematics 2018-12-05 Anitha Thillaisundaram

For each prime p and a monic polynomial f, invertible over p, we define a group G_{p,f} of p-adic automorphisms of the p-ary rooted tree. The groups are modeled after the first Grigorchuk group, which in this setting is the group…

Group Theory · Mathematics 2007-05-23 Zoran Sunic

Firstly, we completely determine the self-similar Hausdorff spectrum of the group of $q$-adic automorphisms where $q$ is a prime power, answering a question of Grigorchuk. Indeed, we take a further step and completely determine its…

Group Theory · Mathematics 2026-01-29 Jorge Fariña-Asategui

We study the pro-$p$ group $G$ whose finite quotients give the prototypical Sylow $p$-subgroup of the general linear groups over a finite field of prime characteristic $p$. In this article, we extend the known results on the subgroup…

Group Theory · Mathematics 2017-01-12 Nadia Mazza

We answer two longstanding questions of Klopsch (1999) and Shalev (2000) by proving that the finitely generated Hausdorff spectrum of the closure of a finitely generated regular branch group with respect to the level-stabilizer filtration…

Group Theory · Mathematics 2025-04-17 Jorge Fariña-Asategui , Oihana Garaialde Ocaña , Jone Uria-Albizuri

A countably based profinite group can be naturally seen as a metric space with respect to a given filtration, and thus, it has a well defined Hausdorff dimension function. Barnea and Shalev found a group theoretical expression for the…

Group Theory · Mathematics 2021-01-26 Iker de las Heras

We prove that the infinitely generated Apollonian gasket has full Hausdorff dimension spectrum. Our proof, which is computer assisted, relies on an iterative technique introduced by the first three authors in [3] and on a flexible method…

Dynamical Systems · Mathematics 2025-04-28 Vasileios Chousionis , Dmitriy Leykekhman , Mariusz Urbański , Erik Wendt

We construct a $2$-generated pro-$2$ group with full normal Hausdorff spectrum $[0,1]$, with respect to each of the four standard filtration series: the $2$-power series, the lower $2$-series, the Frattini series, and the dimension subgroup…

Group Theory · Mathematics 2022-01-14 Iker de las Heras , Anitha Thillaisundaram

The classical Hausdorff dimension of finite or countable sets is zero. We define an analog for finite sets, called finite Hausdorff dimension which is non-trivial. It turns out that a finite bound for the finite Hausdorff dimension…

Discrete Mathematics · Computer Science 2015-08-13 Juan M. Alonso

We study the generalized Hausdorff dimension of some natural subsets of $k^{-1}(3)$, where $k^{-1}(3)$ consists of the real numbers $x$ for which $\left| x-\frac{p}{q} \right|<\frac{1}{(3+\varepsilon)q^2}$ has infinitely many rational…

Number Theory · Mathematics 2026-02-27 Carlos Gustavo Moreira , Harold Erazo , Nicolas Angelini

We study the exact Hausdorff and packing dimensions of the $prime$ $Cantor$ $set$, $\Lambda_P$, which comprises the irrationals whose continued fraction entries are prime numbers. We prove that the Hausdorff measure of the prime Cantor set…

Number Theory · Mathematics 2023-05-22 Tushar Das , David Simmons

Consider all the level sets of a real function. We can group these level sets according to their Hausdorff dimensions. We show that the Hausdorff dimension of the collection of all level sets of a given Hausdorff dimension can be…

Classical Analysis and ODEs · Mathematics 2016-08-29 Gavin Armstrong

L\"uroth series, like regular continued fractions, provide an interesting identification of real numbers with infinite sequences of integers. These sequences give deep arithmetic and measure-theoretic properties of subsets of numbers…

Number Theory · Mathematics 2021-06-07 Aubin Arroyo , Gerardo González Robert
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