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A note on univoque self-sturmian numbers

Jean-Paul Allouche (2008)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

We compare two sets of (infinite) binary sequences whose suffixes satisfy extremal conditions: one occurs when studying iterations of unimodal continuous maps from the unit interval into itself, but it also characterizes univoque real numbers; the other is a disguised version of the set of characteristic sturmian sequences. As a corollary to our study we obtain that a real number β in ( 1 , 2 ) is univoque and self-sturmian if and only if the β -expansion of 1 is of the form 1 v , where v is a characteristic...

A note on univoque self-Sturmian numbers

Jean-Paul Allouche (2010)

RAIRO - Theoretical Informatics and Applications

We compare two sets of (infinite) binary sequences whose suffixes satisfy extremal conditions: one occurs when studying iterations of unimodal continuous maps from the unit interval into itself, but it also characterizes univoque real numbers; the other is a disguised version of the set of characteristic Sturmian sequences. As a corollary to our study we obtain that a real number β in (1,2) is univoque and self-Sturmian if and only if the β-expansion of 1 is of the form 1v, where v is a characteristic...

A problem of Rankin on sets without geometric progressions

Melvyn B. Nathanson, Kevin O'Bryant (2015)

Acta Arithmetica

A geometric progression of length k and integer ratio is a set of numbers of the form a , a r , . . . , a r k - 1 for some positive real number a and integer r ≥ 2. For each integer k ≥ 3, a greedy algorithm is used to construct a strictly decreasing sequence ( a i ) i = 1 of positive real numbers with a₁ = 1 such that the set G ( k ) = i = 1 ( a 2 i , a 2 i - 1 ] contains no geometric progression of length k and integer ratio. Moreover, G ( k ) is a maximal subset of (0,1] that contains no geometric progression of length k and integer ratio. It is also proved that there is...

A propos de la fonction X d’Erdös et Graham

Alain Plagne (2004)

Annales de l’institut Fourier

Nous améliorons les meilleures bornes supérieures et inférieures connues pour la fonction X d’Erdös et Graham définie par X ( h ) = max h 𝒜 max a 𝒜 * ord * ( 𝒜 a ) , où le premier maximum est pris sur toutes les bases (exactes) 𝒜 d’ordre au plus h , où 𝒜 * désigne le sous-ensemble de 𝒜 composé des éléments a tels que 𝒜 { a } soit encore une base et où, enfin, ord * ( 𝒜 ) désigne l’ordre (exact) de 𝒜 . Notre étude nous conduira, entre autres, à prouver un nouveau résultat additif général découlant de la méthode isopérimétrique et à étudier trois problèmes additifs...

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