Chasing finite shadows of infinite groups through geometry

Fuente: arXiv
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Main Author: Bridson, Martin R.
Format: Preprint
Published: 2025
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author Bridson, Martin R.
author_facet Bridson, Martin R.
contents There are many situations in geometry and group theory where it is natural, convenient or necessary to explore infinite groups via their actions on finite objects, i.e. via the finite quotients of the group. But how much understanding can one really gain about an infinite group by examining its finite images? Which properties of the group can one recognise, and when does the set of finite images determine the group completely? How hard is it to decide what the finite images of a given infinite group are? These notes follow my plenary lecture at the ECM in Sevilla, July 2024. The goal of the lecture was to sketch some of the rich history of the preceding problems and to present results that illustrate how the field surrounding these questions has been transformed in recent years by input from low-dimensional topology and the study of non-positively curved spaces.
format Preprint
id arxiv_https___arxiv_org_abs_2504_11684
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Chasing finite shadows of infinite groups through geometry
Bridson, Martin R.
Group Theory
Geometric Topology
20E18, 20E26, 20F67, 57K32
There are many situations in geometry and group theory where it is natural, convenient or necessary to explore infinite groups via their actions on finite objects, i.e. via the finite quotients of the group. But how much understanding can one really gain about an infinite group by examining its finite images? Which properties of the group can one recognise, and when does the set of finite images determine the group completely? How hard is it to decide what the finite images of a given infinite group are? These notes follow my plenary lecture at the ECM in Sevilla, July 2024. The goal of the lecture was to sketch some of the rich history of the preceding problems and to present results that illustrate how the field surrounding these questions has been transformed in recent years by input from low-dimensional topology and the study of non-positively curved spaces.
title Chasing finite shadows of infinite groups through geometry
topic Group Theory
Geometric Topology
20E18, 20E26, 20F67, 57K32
url https://arxiv.org/abs/2504.11684