English

Maximal run-length function with constraints: a generalization of the Erd\H{o}s-R\'enyi limit theorem and the exceptional sets

Classical Analysis and ODEs 2022-12-12 v1

Abstract

Let A={Ai}i=1\mathbf{A}=\{A_i\}_{i=1}^{\infty} be a sequence of sets with each AiA_i being a non-empty collection of 00-11 sequences of length ii. For x[0,1)x\in [0,1), the maximal run-length function n(x,A)\ell_n(x,\mathbf{A}) (with respect to A\mathbf{A}) is defined to the largest kk such that in the first nn digits of the dyadic expansion of xx there is a consecutive subsequence contained in AkA_k. Suppose that limn(log2An)/n=τ\lim_{n\to\infty}(\log_2|A_n|)/n=\tau for some τ[0,1]\tau\in [0,1] and one additional assumption holds, we prove a generalization of the Erd\H{o}s-R\'enyi limit theorem which states that limnn(x,A)log2n=11τ\lim_{n\to\infty}\frac{\ell_n(x,\mathbf{A})}{\log_2n}=\frac{1}{1-\tau} for Lebesgue almost all x[0,1)x\in [0,1). For the exceptional sets, we prove under a certain stronger assumption on A\mathbf{A} that the set {x[0,1):limnn(x,A)log2n=0 and limnn(x,A)=}\left\{x\in [0,1): \lim_{n\to\infty}\frac{\ell_n(x,\mathbf{A})}{\log_2n}=0\text{ and } \lim_{n\to\infty}\ell_n(x,\mathbf{A})=\infty\right\} has Hausdorff dimension at least 1τ1-\tau.

Keywords

Cite

@article{arxiv.2212.04714,
  title  = {Maximal run-length function with constraints: a generalization of the Erd\H{o}s-R\'enyi limit theorem and the exceptional sets},
  author = {Yu-Feng Wu},
  journal= {arXiv preprint arXiv:2212.04714},
  year   = {2022}
}