Automatic logarithm and associated measures

We introduce the notion of the automatic logarithm \(\operatorname{Log}_{\mathcal A}(\mathcal B)\) of a finite initial Mealy automaton \(\mathcal B\), with another automaton \(\mathcal A\) as the base. It allows one to find for any input word \(w\) a power \(n\) such that \(\mathcal B(w)=\mathcal A^...

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Date:2023
Main Authors: Grigorchuk, R., Kogan, R., Vorobets, Y.
Format: Article
Language:English
Published: Lugansk National Taras Shevchenko University 2023
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Online Access:https://admjournal.luguniv.edu.ua/index.php/adm/article/view/2014
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Journal Title:Algebra and Discrete Mathematics

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Algebra and Discrete Mathematics
id admjournalluguniveduua-article-2014
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spelling admjournalluguniveduua-article-20142023-02-08T16:55:57Z Automatic logarithm and associated measures Grigorchuk, R. Kogan, R. Vorobets, Y. Mealy automaton, Moore machine, regular rooted tree, Markov measure, finite-state measure 20E08, 37B10, 60B05, 68Q45 We introduce the notion of the automatic logarithm \(\operatorname{Log}_{\mathcal A}(\mathcal B)\) of a finite initial Mealy automaton \(\mathcal B\), with another automaton \(\mathcal A\) as the base. It allows one to find for any input word \(w\) a power \(n\) such that \(\mathcal B(w)=\mathcal A^n(w)\). The purpose is to study the expanding properties of graphs describing the action of the group generated by \(\mathcal A\) and \(\mathcal B\) on input words of a fixed length interpreted as levels of a regular \(d\)-ary rooted tree \(\mathcal T\). Formally, the automatic logarithm is a single map \(\operatorname{Log}_{\mathcal A}(\mathcal B)\colon\partial \mathcal T \rightarrow \mathbb{Z}_d\) from the boundary of the tree to the \(d\)-adic integers. Under the assumption that the action of the automaton \(\mathcal A\) on the tree \(\mathcal T\) is level-transitive and of bounded activity, we show that \(\operatorname{Log}_{\mathcal A}(\mathcal B)\) can be computed by a Moore machine. The distribution of values of the automatic logarithm yields a probabilistic measure \(\mu\) on \(\partial \mathcal T\), which in some cases can be computed by a Mealy-type machine (we then say that \(\mu\) is finite-state). We provide a criterion to determine whether \(\mu\) is finite-state. A number of examples with \(\mathcal A\) being the adding machine are considered. Lugansk National Taras Shevchenko University 2023-02-08 Article Article Peer-reviewed Article application/pdf https://admjournal.luguniv.edu.ua/index.php/adm/article/view/2014 10.12958/adm2014 Algebra and Discrete Mathematics; Vol 34, No 1 (2022) 2415-721X 1726-3255 en https://admjournal.luguniv.edu.ua/index.php/adm/article/view/2014/pdf https://admjournal.luguniv.edu.ua/index.php/adm/article/downloadSuppFile/2014/1004 https://admjournal.luguniv.edu.ua/index.php/adm/article/downloadSuppFile/2014/1005 https://admjournal.luguniv.edu.ua/index.php/adm/article/downloadSuppFile/2014/1006 Copyright (c) 2023 Algebra and Discrete Mathematics
institution Algebra and Discrete Mathematics
baseUrl_str
datestamp_date 2023-02-08T16:55:57Z
collection OJS
language English
topic Mealy automaton
Moore machine
regular rooted tree
Markov measure
finite-state measure
20E08
37B10
60B05
68Q45
spellingShingle Mealy automaton
Moore machine
regular rooted tree
Markov measure
finite-state measure
20E08
37B10
60B05
68Q45
Grigorchuk, R.
Kogan, R.
Vorobets, Y.
Automatic logarithm and associated measures
topic_facet Mealy automaton
Moore machine
regular rooted tree
Markov measure
finite-state measure
20E08
37B10
60B05
68Q45
format Article
author Grigorchuk, R.
Kogan, R.
Vorobets, Y.
author_facet Grigorchuk, R.
Kogan, R.
Vorobets, Y.
author_sort Grigorchuk, R.
title Automatic logarithm and associated measures
title_short Automatic logarithm and associated measures
title_full Automatic logarithm and associated measures
title_fullStr Automatic logarithm and associated measures
title_full_unstemmed Automatic logarithm and associated measures
title_sort automatic logarithm and associated measures
description We introduce the notion of the automatic logarithm \(\operatorname{Log}_{\mathcal A}(\mathcal B)\) of a finite initial Mealy automaton \(\mathcal B\), with another automaton \(\mathcal A\) as the base. It allows one to find for any input word \(w\) a power \(n\) such that \(\mathcal B(w)=\mathcal A^n(w)\). The purpose is to study the expanding properties of graphs describing the action of the group generated by \(\mathcal A\) and \(\mathcal B\) on input words of a fixed length interpreted as levels of a regular \(d\)-ary rooted tree \(\mathcal T\). Formally, the automatic logarithm is a single map \(\operatorname{Log}_{\mathcal A}(\mathcal B)\colon\partial \mathcal T \rightarrow \mathbb{Z}_d\) from the boundary of the tree to the \(d\)-adic integers. Under the assumption that the action of the automaton \(\mathcal A\) on the tree \(\mathcal T\) is level-transitive and of bounded activity, we show that \(\operatorname{Log}_{\mathcal A}(\mathcal B)\) can be computed by a Moore machine. The distribution of values of the automatic logarithm yields a probabilistic measure \(\mu\) on \(\partial \mathcal T\), which in some cases can be computed by a Mealy-type machine (we then say that \(\mu\) is finite-state). We provide a criterion to determine whether \(\mu\) is finite-state. A number of examples with \(\mathcal A\) being the adding machine are considered.
publisher Lugansk National Taras Shevchenko University
publishDate 2023
url https://admjournal.luguniv.edu.ua/index.php/adm/article/view/2014
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first_indexed 2025-12-02T15:35:19Z
last_indexed 2025-12-02T15:35:19Z
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