Snowflake groups and conjugator length functions with non-integer exponents

Fuente: arXiv
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Autori principali: Bridson, Martin R., Riley, Timothy R.
Natura: Preprint
Pubblicazione: 2025
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author Bridson, Martin R.
Riley, Timothy R.
author_facet Bridson, Martin R.
Riley, Timothy R.
contents We exhibit novel geometric phenomena in the study of conjugacy problems for discrete groups. We prove that the snowflake groups $B_{pq}$, indexed by pairs of positive integers $p>q$, have conjugator length functions $\text{CL}(n)\simeq n$ and annular Dehn functions $\text{Ann}(n) \simeq n^{2α}$, where $α= \log_2(2p/q)$. Then, building on $B_{pq}$, we construct groups $\tilde{B}_{pq}^+$, for which $\text{CL}(n)\simeq n^{α+1}$. Thus the conjugator length spectrum and the spectrum of exponents of annular Dehn functions are both dense in the range $[2,\infty)$.
format Preprint
id arxiv_https___arxiv_org_abs_2512_14038
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Snowflake groups and conjugator length functions with non-integer exponents
Bridson, Martin R.
Riley, Timothy R.
Group Theory
20F65 (Primary), 20F10 (Secondary)
We exhibit novel geometric phenomena in the study of conjugacy problems for discrete groups. We prove that the snowflake groups $B_{pq}$, indexed by pairs of positive integers $p>q$, have conjugator length functions $\text{CL}(n)\simeq n$ and annular Dehn functions $\text{Ann}(n) \simeq n^{2α}$, where $α= \log_2(2p/q)$. Then, building on $B_{pq}$, we construct groups $\tilde{B}_{pq}^+$, for which $\text{CL}(n)\simeq n^{α+1}$. Thus the conjugator length spectrum and the spectrum of exponents of annular Dehn functions are both dense in the range $[2,\infty)$.
title Snowflake groups and conjugator length functions with non-integer exponents
topic Group Theory
20F65 (Primary), 20F10 (Secondary)
url https://arxiv.org/abs/2512.14038