Cusped spaces for hierarchically hyperbolic groups, and applications to Dehn filling quotients

Fuente: arXiv
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Main Authors: Mangioni, Giorgio, Sisto, Alessandro
Format: Preprint
Published: 2026
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author Mangioni, Giorgio
Sisto, Alessandro
author_facet Mangioni, Giorgio
Sisto, Alessandro
contents We introduce a construction that simultaneously yields cusped spaces of relatively hyperbolic groups, and spaces quasi-isometric to Teichmueller metrics. We use this to study Dehn-filling-like quotients of various groups, among which mapping class groups of punctured spheres. In particular, we show that the mapping class group of a five-holed sphere (resp. the braid group on four strands) has infinite hyperbolic quotients (strongly) not isomorphic to hyperbolic quotients of any other given sphere mapping class group (resp. any other braid group). These quotients are obtained by modding out suitable large powers of Dehn twists, and we further argue that the corresponding quotients of the extended mapping class group have trivial outer automorphism groups. We obtain these results by studying torsion elements in the relevant quotients.
format Preprint
id arxiv_https___arxiv_org_abs_2602_23275
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Cusped spaces for hierarchically hyperbolic groups, and applications to Dehn filling quotients
Mangioni, Giorgio
Sisto, Alessandro
Geometric Topology
Group Theory
20F65 (Primary), 57K20, 20F36, 20F67 (Secondary)
We introduce a construction that simultaneously yields cusped spaces of relatively hyperbolic groups, and spaces quasi-isometric to Teichmueller metrics. We use this to study Dehn-filling-like quotients of various groups, among which mapping class groups of punctured spheres. In particular, we show that the mapping class group of a five-holed sphere (resp. the braid group on four strands) has infinite hyperbolic quotients (strongly) not isomorphic to hyperbolic quotients of any other given sphere mapping class group (resp. any other braid group). These quotients are obtained by modding out suitable large powers of Dehn twists, and we further argue that the corresponding quotients of the extended mapping class group have trivial outer automorphism groups. We obtain these results by studying torsion elements in the relevant quotients.
title Cusped spaces for hierarchically hyperbolic groups, and applications to Dehn filling quotients
topic Geometric Topology
Group Theory
20F65 (Primary), 57K20, 20F36, 20F67 (Secondary)
url https://arxiv.org/abs/2602.23275