Semidirect Product Decompositions for Periodic Regular Languages

Fuente: arXiv
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Autori principali: Inoue, Yusuke, Hashimoto, Kenji, Seki, Hiroyuki
Natura: Preprint
Pubblicazione: 2024
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author Inoue, Yusuke
Hashimoto, Kenji
Seki, Hiroyuki
author_facet Inoue, Yusuke
Hashimoto, Kenji
Seki, Hiroyuki
contents The definition of period in finite-state Markov chains can be extended to regular languages by considering the transitions of DFAs accepting them. For example, the language $(ΣΣ)^*$ has period two because the length of a recursion (cycle) in its DFA must be even. This paper shows that the period of a regular language appears as a cyclic group within its syntactic monoid. Specifically, we show that a regular language has period $P$ if and only if its syntactic monoid is isomorphic to a submonoid of a semidirect product between a specific finite monoid and the cyclic group of order $P$. Moreover, we explore the relation between the structure of Markov chains and our result, and apply this relation to the theory of probabilities of languages. We also discuss the Krohn-Rhodes decomposition of finite semigroups, which is strongly linked to our methods.
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id arxiv_https___arxiv_org_abs_2403_05088
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Semidirect Product Decompositions for Periodic Regular Languages
Inoue, Yusuke
Hashimoto, Kenji
Seki, Hiroyuki
Formal Languages and Automata Theory
68Q45, 68Q70
The definition of period in finite-state Markov chains can be extended to regular languages by considering the transitions of DFAs accepting them. For example, the language $(ΣΣ)^*$ has period two because the length of a recursion (cycle) in its DFA must be even. This paper shows that the period of a regular language appears as a cyclic group within its syntactic monoid. Specifically, we show that a regular language has period $P$ if and only if its syntactic monoid is isomorphic to a submonoid of a semidirect product between a specific finite monoid and the cyclic group of order $P$. Moreover, we explore the relation between the structure of Markov chains and our result, and apply this relation to the theory of probabilities of languages. We also discuss the Krohn-Rhodes decomposition of finite semigroups, which is strongly linked to our methods.
title Semidirect Product Decompositions for Periodic Regular Languages
topic Formal Languages and Automata Theory
68Q45, 68Q70
url https://arxiv.org/abs/2403.05088