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A new lower bound for ( 3 / 2 ) k

Wadim Zudilin (2007)

Journal de Théorie des Nombres de Bordeaux

We prove that, for all integers k exceeding some effectively computable number  K , the distance from ( 3 / 2 ) k to the nearest integer is greater than 0 . 5803 k .

Automates finis et ensembles normaux

Christian Mauduit (1986)

Annales de l'institut Fourier

Soit u = ( u n ) n N une suite strictement croissante d’entiers reconnaissable par un automate fini. Nous montrons qu’une condition nécessaire et suffisante pour que l’ensemble normal associé a u soit exactement R Q est que l’un au moins des sommets qui reconnaît la suite u soit précédé dans le graphe de l’automate par un sommet possédant au moins deux circuits fermés distincts. Cette condition peut se traduire quantitativement en disant que la suite u doit être plus “dense” que toute suite exponentielle.

Characterizations of groups generated by Kronecker sets

András Biró (2007)

Journal de Théorie des Nombres de Bordeaux

In recent years, starting with the paper [B-D-S], we have investigated the possibility of characterizing countable subgroups of the torus T = R / Z by subsets of Z . Here we consider new types of subgroups: let K T be a Kronecker set (a compact set on which every continuous function f : K T can be uniformly approximated by characters of T ), and G the group generated by K . We prove (Theorem 1) that G can be characterized by a subset of Z 2 (instead of a subset of Z ). If K is finite, Theorem 1 implies our earlier result...

Comments on the fractional parts of Pisot numbers

Toufik Zaïmi, Mounia Selatnia, Hanifa Zekraoui (2015)

Archivum Mathematicum

Let L ( θ , λ ) be the set of limit points of the fractional parts { λ θ n } , n = 0 , 1 , 2 , , where θ is a Pisot number and λ ( θ ) . Using a description of L ( θ , λ ) , due to Dubickas, we show that there is a sequence ( λ n ) n 0 of elements of ( θ ) such that Card ( L ( θ , λ n ) ) < Card ( L ( θ , λ n + 1 ) ) , n 0 . Also, we prove that the...

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