Freiheitssatz and phase transition for the density model of random groups

Fuente: arXiv
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Auteur principal: Tsai, Tsung-Hsuan
Format: Preprint
Publié: 2021
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author Tsai, Tsung-Hsuan
author_facet Tsai, Tsung-Hsuan
contents Magnus' Freiheitssatz states that if a group is defined by a presentation with $m$ generators and a single relator containing the last generating letter, then the first $m-1$ letters freely generate a free subgroup. We study an analogue of this theorem in the Gromov density model of random groups, showing a phase transition phenomenon at density $d_r = \min\{\frac{1}{2}, 1-\log_{2m-1}(2r-1)\}$ with $1\leq r\leq m-1$: we prove that for a random group with $m$ generators at density $d$, if $d < d_r$ then the first $r$ letters freely generate a free subgroup; whereas if $d > d_r$ then the first $r$ letters generate the whole group.
format Preprint
id arxiv_https___arxiv_org_abs_2111_08958
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Freiheitssatz and phase transition for the density model of random groups
Tsai, Tsung-Hsuan
Group Theory
Probability
2020: 20F05, 20F06
Magnus' Freiheitssatz states that if a group is defined by a presentation with $m$ generators and a single relator containing the last generating letter, then the first $m-1$ letters freely generate a free subgroup. We study an analogue of this theorem in the Gromov density model of random groups, showing a phase transition phenomenon at density $d_r = \min\{\frac{1}{2}, 1-\log_{2m-1}(2r-1)\}$ with $1\leq r\leq m-1$: we prove that for a random group with $m$ generators at density $d$, if $d < d_r$ then the first $r$ letters freely generate a free subgroup; whereas if $d > d_r$ then the first $r$ letters generate the whole group.
title Freiheitssatz and phase transition for the density model of random groups
topic Group Theory
Probability
2020: 20F05, 20F06
url https://arxiv.org/abs/2111.08958