Spectral properties of arithmetic functions
This paper is closely related to the paper of Harry I. Miller: Measure theoretical subsequence characterization of statistical convergence, Trans. Amer. Math. Soc. 347 (1995), 1811–1819 and contains a general investigation of statistical convergence of subsequences of an arbitrary sequence from the point of view of Lebesgue measure, Hausdorff dimensions and Baire’s categories.
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 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.
In this paper we study the structure of the projections of the finite cutting segments corresponding to unimodular substitutions over a two-letter alphabet. We show that such a projection is a block of letters if and only if the substitution is Sturmian. Applying the procedure of projecting the cutting segments corresponding to a Christoffel substitution twice results in the original substitution. This induces a duality on the set of Christoffel substitutions.
À tout ensemble d’entiers positifs, on attache un nombre , éventuellement infini nommé fréquence de cet ensemble et mesurant la longueur relative des tranches d’entiers consécutifs de cet ensemble. La notion de fréquence présente peu de rapport avec celle de densité et par exemple un ensemble et son complémentaire peuvent être tous deux de fréquence infinie.Les deux principaux résultats sont alors les suivants :1.- Soit algébrique. La condition nécessaire et suffisante pour qu’existe un ensemble...