Mapped Exponent and Asymptotic Critical Exponent of Words

Fuente: arXiv
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Main Authors: Foster, Eva, Saarela, Aleksi, Vanhatalo, Aleksi
Format: Preprint
Published: 2025
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author Foster, Eva
Saarela, Aleksi
Vanhatalo, Aleksi
author_facet Foster, Eva
Saarela, Aleksi
Vanhatalo, Aleksi
contents We study how much injective morphisms can increase the repetitiveness of a given word. This question has a few possible variations depending on the meaning of ``repetitiveness''. We concentrate on fractional exponents of finite words and asymptotic critical exponents of infinite words. We characterize finite words that, when mapped by injective morphisms, can have arbitrarily high fractional exponent. For infinite words, alongside other results, we show that the asymptotic critical exponent grows at most by a constant factor (depending on the size of the alphabet) when mapped by an injective morphism. For both finite and infinite words, the binary case is better understood than the general case.
format Preprint
id arxiv_https___arxiv_org_abs_2506_04091
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Mapped Exponent and Asymptotic Critical Exponent of Words
Foster, Eva
Saarela, Aleksi
Vanhatalo, Aleksi
Combinatorics
Formal Languages and Automata Theory
68R15
We study how much injective morphisms can increase the repetitiveness of a given word. This question has a few possible variations depending on the meaning of ``repetitiveness''. We concentrate on fractional exponents of finite words and asymptotic critical exponents of infinite words. We characterize finite words that, when mapped by injective morphisms, can have arbitrarily high fractional exponent. For infinite words, alongside other results, we show that the asymptotic critical exponent grows at most by a constant factor (depending on the size of the alphabet) when mapped by an injective morphism. For both finite and infinite words, the binary case is better understood than the general case.
title Mapped Exponent and Asymptotic Critical Exponent of Words
topic Combinatorics
Formal Languages and Automata Theory
68R15
url https://arxiv.org/abs/2506.04091