Displaying similar documents to “Periodicity problem of substitutions over ternary alphabets”

A length bound for binary equality words

Jana Hadravová (2011)

Commentationes Mathematicae Universitatis Carolinae

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Let w be an equality word of two binary non-periodic morphisms g , h : { a , b } * → Δ * with unique overflows. It is known that if w contains at least 25 occurrences of each of the letters a and b , then it has to have one of the following special forms: up to the exchange of the letters a and b either w = ( a b ) i a , or w = a i b j with gcd ( i , j ) = 1 . We will generalize the result, justify this bound and prove that it can be lowered to nine occurrences of each of the letters a and b .

Directive words of episturmian words : equivalences and normalization

Amy Glen, Florence Levé, Gwénaël Richomme (2009)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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Episturmian morphisms constitute a powerful tool to study episturmian words. Indeed, any episturmian word can be infinitely decomposed over the set of pure episturmian morphisms. Thus, an episturmian word can be defined by one of its morphic decompositions or, equivalently, by a certain directive word. Here we characterize pairs of words directing the same episturmian word. We also propose a way to uniquely define any episturmian word through a normalization of its directive words. As...

Some Algebraic Properties of Machine Poset of Infinite Words

Aleksandrs Belovs (2008)

RAIRO - Theoretical Informatics and Applications

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The complexity of infinite words is considered from the point of view of a transformation with a Mealy machine that is the simplest model of a finite automaton transducer. We are mostly interested in algebraic properties of the underlying partially ordered set. Results considered with the existence of supremum, infimum, antichains, chains and density aspects are investigated.