Counting automorphic orbits in finitely generated groups

Fuente: arXiv
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Main Authors: Elliott, Luna, Evetts, Alex, Levine, Alex
Format: Preprint
Published: 2026
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author Elliott, Luna
Evetts, Alex
Levine, Alex
author_facet Elliott, Luna
Evetts, Alex
Levine, Alex
contents We study an analogue of the conjugacy growth function in finitely generated groups: the automorphic growth function. This counts the number of automorphic orbits that intersect the ball of radius $n$ in the group. We show that this is not a commensurability invariant, by giving virtually abelian counterexamples. We classify the automorphic growth rate of all virtually abelian groups of rank at most $2$, the Heisenberg group, finite rank free groups and Thompson's groups $T$ and $V$. This last computation allows to conclude that $T$ and $V$ have exponential conjugacy growth.
format Preprint
id arxiv_https___arxiv_org_abs_2604_18104
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Counting automorphic orbits in finitely generated groups
Elliott, Luna
Evetts, Alex
Levine, Alex
Group Theory
20F69, 20F65, 20F28
We study an analogue of the conjugacy growth function in finitely generated groups: the automorphic growth function. This counts the number of automorphic orbits that intersect the ball of radius $n$ in the group. We show that this is not a commensurability invariant, by giving virtually abelian counterexamples. We classify the automorphic growth rate of all virtually abelian groups of rank at most $2$, the Heisenberg group, finite rank free groups and Thompson's groups $T$ and $V$. This last computation allows to conclude that $T$ and $V$ have exponential conjugacy growth.
title Counting automorphic orbits in finitely generated groups
topic Group Theory
20F69, 20F65, 20F28
url https://arxiv.org/abs/2604.18104