Constructing reducibly geometrically finite subgroups of the mapping class group

Fuente: arXiv
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Autori principali: Aougab, Tarik, Bray, Harrison, Dowdall, Spencer, Hoganson, Hannah, Maloni, Sara, Whitfield, Brandis
Natura: Preprint
Pubblicazione: 2025
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author Aougab, Tarik
Bray, Harrison
Dowdall, Spencer
Hoganson, Hannah
Maloni, Sara
Whitfield, Brandis
author_facet Aougab, Tarik
Bray, Harrison
Dowdall, Spencer
Hoganson, Hannah
Maloni, Sara
Whitfield, Brandis
contents In this article, we consider qualified notions of geometric finiteness in mapping class groups called parabolically geometrically finite (PGF) and reducibly geometrically finite (RGF). We examine several constructions of subgroups and determine when they produce a PGF or RGF subgroup. These results provide a variety of new examples of PGF and RGF subgroups. Firstly, we consider the right-angled Artin subgroups constructed by Koberda and Clay--Leininger--Mangahas, which are generated by high powers of given elements of the mapping class group. We give conditions on the supports of these elements that imply the resulting right-angled Artin subgroup is RGF. Secondly, we prove combination theorems which provide conditions for when a collection of reducible subgroups, or sufficiently deep finite-index subgroups thereof, generate an RGF subgroup.
format Preprint
id arxiv_https___arxiv_org_abs_2501_13234
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Constructing reducibly geometrically finite subgroups of the mapping class group
Aougab, Tarik
Bray, Harrison
Dowdall, Spencer
Hoganson, Hannah
Maloni, Sara
Whitfield, Brandis
Geometric Topology
Group Theory
20F65, 20F67, 57K20, 57M60
In this article, we consider qualified notions of geometric finiteness in mapping class groups called parabolically geometrically finite (PGF) and reducibly geometrically finite (RGF). We examine several constructions of subgroups and determine when they produce a PGF or RGF subgroup. These results provide a variety of new examples of PGF and RGF subgroups. Firstly, we consider the right-angled Artin subgroups constructed by Koberda and Clay--Leininger--Mangahas, which are generated by high powers of given elements of the mapping class group. We give conditions on the supports of these elements that imply the resulting right-angled Artin subgroup is RGF. Secondly, we prove combination theorems which provide conditions for when a collection of reducible subgroups, or sufficiently deep finite-index subgroups thereof, generate an RGF subgroup.
title Constructing reducibly geometrically finite subgroups of the mapping class group
topic Geometric Topology
Group Theory
20F65, 20F67, 57K20, 57M60
url https://arxiv.org/abs/2501.13234