English

On series of translates of positive functions III

Classical Analysis and ODEs 2018-01-31 v1

Abstract

Suppose Λ\Lambda is a discrete infinite set of nonnegative real numbers. We say that Λ {\Lambda} is of type 1 if the series s(x)=λΛf(x+λ)s(x)=\sum_{\lambda\in\Lambda}f(x+\lambda) satisfies a zero-one law. This means that for any non-negative measurable f:R[0,+)f: { {\mathbb R}}\to [0,+ {\infty}) either the convergence set C(f,Λ)={x:s(x)<+}=RC(f, {\Lambda})=\{x: s(x)<+ {\infty} \}= { {\mathbb R}} modulo sets of Lebesgue zero, or its complement the divergence set D(f,Λ)={x:s(x)=+}=RD(f, {\Lambda})=\{x: s(x)=+ {\infty} \}= { {\mathbb R}} modulo sets of measure zero. If Λ {\Lambda} is not of type 1 we say that Λ {\Lambda} is of type 2. In this paper we show that there is a universal Λ {\Lambda} with gaps monotone decreasingly converging to zero such that for any open subset GRG \subset { {\mathbb R}} one can find a characteristic function fGf_{G} such that GD(fG,Λ)G \subset D(f_G, {\Lambda}) and C(fG,Λ)=RGC(f_G, {\Lambda})= { {\mathbb R}} {\setminus} G modulo sets of measure zero. We also consider the question whether C(f,Λ)C(f, {\Lambda}) can contain non-degenerate intervals for continuous functions when D(f,Λ)D(f, {\Lambda}) is of positive measure. The above results answer some questions raised in a paper of Z. Buczolich, J-P. Kahane, and D. Mauldin.

Keywords

Cite

@article{arxiv.1801.09935,
  title  = {On series of translates of positive functions III},
  author = {Zoltán Buczolich and Balázs Maga and Gáspár Vértesy},
  journal= {arXiv preprint arXiv:1801.09935},
  year   = {2018}
}