On the orbits of automaton semigroups and groups

We investigate the orbits of automaton semigroups and groups to obtain algorithmic and structural results, both for general automata but also for some special subclasses.First, we show that a more general version of the finiteness problem for automaton groups is undecidable. This problem is equivale...

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Дата:2022
Автори: D'Angeli, D., Francoeur, D., Rodaro, E., Wächter, J. Ph.
Формат: Стаття
Мова:Англійська
Опубліковано: Lugansk National Taras Shevchenko University 2022
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Онлайн доступ:https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1692
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Назва журналу:Algebra and Discrete Mathematics

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Algebra and Discrete Mathematics
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author D'Angeli, D.
Francoeur, D.
Rodaro, E.
Wächter, J. Ph.
author_facet D'Angeli, D.
Francoeur, D.
Rodaro, E.
Wächter, J. Ph.
author_sort D'Angeli, D.
baseUrl_str
collection OJS
datestamp_date 2023-02-23T09:59:31Z
description We investigate the orbits of automaton semigroups and groups to obtain algorithmic and structural results, both for general automata but also for some special subclasses.First, we show that a more general version of the finiteness problem for automaton groups is undecidable. This problem is equivalent to the finiteness problem for left principal ideals in automaton semigroups generated by complete and reversible automata.Then, we look at \(\omega\)-word (i.\,e.\ right infinite words) with a finite orbit. We show that every automaton yielding an \(\omega\)-word with a finite orbit already yields an ultimately periodic one, which is not periodic in general, however. On the algorithmic side, we observe that it is not possible to decide whether a given periodic \(\omega\)-word has an infinite orbit and that we cannot check whether a given reversible and complete automaton admits an \(\omega\)-word with a finite orbit, a reciprocal problem to the finiteness problem for automaton semigroups in the reversible case.Finally, we look at automaton groups generated by reversible but not bi-reversible automata and show that many words have infinite orbits under the action of such automata.
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spelling admjournalluguniveduua-article-16922023-02-23T09:59:31Z On the orbits of automaton semigroups and groups D'Angeli, D. Francoeur, D. Rodaro, E. Wächter, J. Ph. automaton groups, automaton semigroups, orbits, Schreier graphs, orbital graphs, reversible 20E99, 20F10, 20M30, 20M35, 68Q70 We investigate the orbits of automaton semigroups and groups to obtain algorithmic and structural results, both for general automata but also for some special subclasses.First, we show that a more general version of the finiteness problem for automaton groups is undecidable. This problem is equivalent to the finiteness problem for left principal ideals in automaton semigroups generated by complete and reversible automata.Then, we look at \(\omega\)-word (i.\,e.\ right infinite words) with a finite orbit. We show that every automaton yielding an \(\omega\)-word with a finite orbit already yields an ultimately periodic one, which is not periodic in general, however. On the algorithmic side, we observe that it is not possible to decide whether a given periodic \(\omega\)-word has an infinite orbit and that we cannot check whether a given reversible and complete automaton admits an \(\omega\)-word with a finite orbit, a reciprocal problem to the finiteness problem for automaton semigroups in the reversible case.Finally, we look at automaton groups generated by reversible but not bi-reversible automata and show that many words have infinite orbits under the action of such automata. Lugansk National Taras Shevchenko University 2022-06-15 Article Article Peer-reviewed Article application/pdf https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1692 10.12958/adm1692 Algebra and Discrete Mathematics; Vol 33, No 1 (2022) 2415-721X 1726-3255 en https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1692/pdf_1 https://admjournal.luguniv.edu.ua/index.php/adm/article/downloadSuppFile/1692/773 https://admjournal.luguniv.edu.ua/index.php/adm/article/downloadSuppFile/1692/774 https://admjournal.luguniv.edu.ua/index.php/adm/article/downloadSuppFile/1692/775 Copyright (c) 2022 Algebra and Discrete Mathematics
spellingShingle automaton groups
automaton semigroups
orbits
Schreier graphs
orbital graphs
reversible
20E99
20F10
20M30
20M35
68Q70
D'Angeli, D.
Francoeur, D.
Rodaro, E.
Wächter, J. Ph.
On the orbits of automaton semigroups and groups
title On the orbits of automaton semigroups and groups
title_full On the orbits of automaton semigroups and groups
title_fullStr On the orbits of automaton semigroups and groups
title_full_unstemmed On the orbits of automaton semigroups and groups
title_short On the orbits of automaton semigroups and groups
title_sort on the orbits of automaton semigroups and groups
topic automaton groups
automaton semigroups
orbits
Schreier graphs
orbital graphs
reversible
20E99
20F10
20M30
20M35
68Q70
topic_facet automaton groups
automaton semigroups
orbits
Schreier graphs
orbital graphs
reversible
20E99
20F10
20M30
20M35
68Q70
url https://admjournal.luguniv.edu.ua/index.php/adm/article/view/1692
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AT francoeurd ontheorbitsofautomatonsemigroupsandgroups
AT rodaroe ontheorbitsofautomatonsemigroupsandgroups
AT wachterjph ontheorbitsofautomatonsemigroupsandgroups