Displaying similar documents to “The minimal density of a letter in an infinite ternary square-free word is 883/3215.”

Words and repeated factors.

Carpi, Arturo, de Luca, Aldo (1999)

Séminaire Lotharingien de Combinatoire [electronic only]

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Palindromic complexity of infinite words associated with simple Parry numbers

Petr Ambrož, Zuzana Masáková, Edita Pelantová, Christiane Frougny (2006)

Annales de l’institut Fourier

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A simple Parry number is a real number β > 1 such that the Rényi expansion of 1 is finite, of the form d β ( 1 ) = t 1 t m . We study the palindromic structure of infinite aperiodic words u β that are the fixed point of a substitution associated with a simple Parry number β . It is shown that the word u β contains infinitely many palindromes if and only if t 1 = t 2 = = t m - 1 t m . Numbers β satisfying this condition are the so-called Pisot numbers. If t m = 1 then u β is an Arnoux-Rauzy word. We show that if β is a confluent Pisot number then...

Complexity of testing morphic primitivity

Štěpán Holub, Vojtěch Matocha (2013)

Kybernetika

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We analyze an algorithm that decides whether a given word is a fixed point of a nontrivial morphism. We show that it can be implemented to have complexity in 𝒪 ( m · n ) , where n is the length of the word and m the size of the alphabet.

Substitutions, abstract number systems and the space filling property

Clemens Fuchs, Robert Tijdeman (2006)

Annales de l’institut Fourier

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In this paper we study multi-dimensional words generated by fixed points of substitutions by projecting the integer points on the corresponding broken halfline. We show for a large class of substitutions that the resulting word is the restriction of a linear function modulo 1 and that it can be decided whether the resulting word is space filling or not. The proof uses lattices and the abstract number system associated with the substitution.