Hereditarily just-infinite torsion groups with positive first $\ell^2$-Betti number

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Hauptverfasser: Kionke, Steffen, Schesler, Eduard
Format: Preprint
Veröffentlicht: 2024
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author Kionke, Steffen
Schesler, Eduard
author_facet Kionke, Steffen
Schesler, Eduard
contents We present a new method to construct finitely generated, residually finite, infinite torsion groups. In contrast to known constructions, a profinite perspective enables us to control finite quotients and normal subgroups of these torsion groups. As an application, we describe the first examples of residually finite, hereditarily just-infinite groups with positive first $\ell^2$-Betti-number. In addition, we show that these groups have polynomial normal subgroup growth, which answers a question of Barnea and Schlage-Puchta.
format Preprint
id arxiv_https___arxiv_org_abs_2401_04542
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Hereditarily just-infinite torsion groups with positive first $\ell^2$-Betti number
Kionke, Steffen
Schesler, Eduard
Group Theory
20E26, 20E07, 20E18, 20C05
We present a new method to construct finitely generated, residually finite, infinite torsion groups. In contrast to known constructions, a profinite perspective enables us to control finite quotients and normal subgroups of these torsion groups. As an application, we describe the first examples of residually finite, hereditarily just-infinite groups with positive first $\ell^2$-Betti-number. In addition, we show that these groups have polynomial normal subgroup growth, which answers a question of Barnea and Schlage-Puchta.
title Hereditarily just-infinite torsion groups with positive first $\ell^2$-Betti number
topic Group Theory
20E26, 20E07, 20E18, 20C05
url https://arxiv.org/abs/2401.04542