Last cases of Dejean's conjecture

M Rao - Theoretical Computer Science, 2011 - Elsevier
Dejean conjectured that the repetition threshold for a k-letter alphabet is kk− 1 when k≥ 5.
Dejean's conjecture has already been proved for k≤ 14 and for k≥ 27. We present here a …

A proof of Dejean's conjecture

J Currie, N Rampersad - Mathematics of computation, 2011 - ams.org
A PROOF OF DEJEAN’S CONJECTURE 1. Introduction Repetitions in words have been
studied since the beginning of the previous cen- Page 1 MATHEMATICS OF COMPUTATION …

Growth properties of power-free languages

AM Shur - Computer Science Review, 2012 - Elsevier
The aim of this paper is to survey the area formed by the intersection of two popular lines of
research in formal language theory. The first line, originated by Thue in 1906, concerns …

[图书][B] Combinatorics, words and symbolic dynamics

V Berthé, M Rigo - 2016 - books.google.com
Internationally recognised researchers look at developing trends in combinatorics with
applications in the study of words and in symbolic dynamics. They explain the important …

The repetition threshold for binary rich words

JD Currie, L Mol, N Rampersad - Discrete Mathematics & …, 2020 - dmtcs.episciences.org
A word of length n is rich if it contains n nonempty palindromic factors. An infinite word is rich
if all of its finite factors are rich. Baranwal and Shallit produced an infinite binary rich word …

Extremal overlap-free and extremal -free binary words

L Mol, N Rampersad, J Shallit - arXiv preprint arXiv:2006.10152, 2020 - arxiv.org
An overlap-free (or $\beta $-free) word $ w $ over a fixed alphabet $\Sigma $ is extremal if
every word obtained from $ w $ by inserting a single letter from $\Sigma $ at any position …

On the growth rates of complexity of threshold languages

AM Shur, IA Gorbunova - RAIRO-Theoretical Informatics and …, 2010 - cambridge.org
Threshold languages, which are the (k/(k–1))+-free languages over k-letter alphabets with
k≥ 5, are the minimal infinite power-free languages according to Dejean's conjecture, which …

The undirected repetition threshold and undirected pattern avoidance

JD Currie, L Mol - Theoretical Computer Science, 2021 - Elsevier
For a rational number r such that 1< r≤ 2, an undirected r-power is a word of the form xyx′,
where the word x is nonempty, the word x′ is in {x, x R}, and we have| xyx′|/| xy|= r. The …

On the number of Dejean words over alphabets of 5, 6, 7, 8, 9 and 10 letters

R Kolpakov, M Rao - Theoretical computer science, 2011 - Elsevier
We give lower bounds on the growth rate of Dejean words, ie minimally repetitive words,
over a k-letter alphabet, for 5≤ k≤ 10. Put together with the known upper bounds, we …

[PDF][PDF] Repetitions in words

N Rampersad, J Shallit - Combinatorics, Words and Symbolic …, 2012 - academia.edu
The study of combinatorics on words dates back at least to the beginning of the 20th century
and the work of Axel Thue [93, 94] on repetitions in words. The study of repetitions in words …