On growth of generalized Grigorchuk's overgroups

Grigorchuk's Overgroup \(\widetilde{\mathcal{G}}\), is a branch group of intermediate growth. It contains the first Grigorchuk's torsion group \(\mathcal{G}\) of intermediate growth constructed in 1980, but also has elements of infinite order. Its growth is substantially greater than the g...

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Date:2020
Main Author: Samarakoon, S. T.
Format: Article
Language:English
Published: Lugansk National Taras Shevchenko University 2020
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Online Access:https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1451
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Journal Title:Algebra and Discrete Mathematics

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Algebra and Discrete Mathematics
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spelling oai:ojs.admjournal.luguniv.edu.ua:article-14512021-01-03T08:55:03Z On growth of generalized Grigorchuk's overgroups Samarakoon, S. T. growth of groups, intermediate growth, Grigorchuk group, growth bounds 20E08 Grigorchuk's Overgroup \(\widetilde{\mathcal{G}}\), is a branch group of intermediate growth. It contains the first Grigorchuk's torsion group \(\mathcal{G}\) of intermediate growth constructed in 1980, but also has elements of infinite order. Its growth is substantially greater than the growth of \(\mathcal{G}\). The group \(\mathcal{G}\), corresponding to the sequence \((012)^\infty = 012012 \dots\), is a member of the family \(\{ G_\omega | \omega \in \Omega = \{ 0, 1, 2 \}^\mathbb{N} \}\) consisting of groups of intermediate growth when sequence \(\omega\) is not eventually constant. Following this construction we define the family \(\{ \widetilde{G}_\omega, \omega \in \Omega \}\) of generalized overgroups. Then \(\widetilde{\mathcal{G}} = \widetilde{G}_{(012)^\infty}\) and \(G_\omega\) is a subgroup of \(\widetilde{G}_\omega\) for each \(\omega \in \Omega\). We prove, if \(\omega\) is eventually constant, then \(\widetilde{G}_\omega\) is of polynomial growth and if \(\omega\) is not eventually constant, then \(\widetilde{G}_\omega\) is of intermediate growth. Lugansk National Taras Shevchenko University 2020-12-30 Article Article Peer-reviewed Article application/pdf https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1451 10.12958/adm1451 Algebra and Discrete Mathematics; Vol 30, No 1 (2020) 2415-721X 1726-3255 en https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1451/pdf https://admjournal.luguniv.edu.ua/index.php/adm/article/downloadSuppFile/1451/579 Copyright (c) 2020 Algebra and Discrete Mathematics
institution Algebra and Discrete Mathematics
baseUrl_str
datestamp_date 2021-01-03T08:55:03Z
collection OJS
language English
topic growth of groups
intermediate growth
Grigorchuk group
growth bounds
20E08
spellingShingle growth of groups
intermediate growth
Grigorchuk group
growth bounds
20E08
Samarakoon, S. T.
On growth of generalized Grigorchuk's overgroups
topic_facet growth of groups
intermediate growth
Grigorchuk group
growth bounds
20E08
format Article
author Samarakoon, S. T.
author_facet Samarakoon, S. T.
author_sort Samarakoon, S. T.
title On growth of generalized Grigorchuk's overgroups
title_short On growth of generalized Grigorchuk's overgroups
title_full On growth of generalized Grigorchuk's overgroups
title_fullStr On growth of generalized Grigorchuk's overgroups
title_full_unstemmed On growth of generalized Grigorchuk's overgroups
title_sort on growth of generalized grigorchuk's overgroups
description Grigorchuk's Overgroup \(\widetilde{\mathcal{G}}\), is a branch group of intermediate growth. It contains the first Grigorchuk's torsion group \(\mathcal{G}\) of intermediate growth constructed in 1980, but also has elements of infinite order. Its growth is substantially greater than the growth of \(\mathcal{G}\). The group \(\mathcal{G}\), corresponding to the sequence \((012)^\infty = 012012 \dots\), is a member of the family \(\{ G_\omega | \omega \in \Omega = \{ 0, 1, 2 \}^\mathbb{N} \}\) consisting of groups of intermediate growth when sequence \(\omega\) is not eventually constant. Following this construction we define the family \(\{ \widetilde{G}_\omega, \omega \in \Omega \}\) of generalized overgroups. Then \(\widetilde{\mathcal{G}} = \widetilde{G}_{(012)^\infty}\) and \(G_\omega\) is a subgroup of \(\widetilde{G}_\omega\) for each \(\omega \in \Omega\). We prove, if \(\omega\) is eventually constant, then \(\widetilde{G}_\omega\) is of polynomial growth and if \(\omega\) is not eventually constant, then \(\widetilde{G}_\omega\) is of intermediate growth.
publisher Lugansk National Taras Shevchenko University
publishDate 2020
url https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1451
work_keys_str_mv AT samarakoonst ongrowthofgeneralizedgrigorchuksovergroups
first_indexed 2025-07-17T10:35:10Z
last_indexed 2025-07-17T10:35:10Z
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