English

A note on the Hitczenko-Kwapien conjecture about a Rademacher sequence

Probability 2023-10-26 v2

Abstract

Let (ϵi)(\epsilon_i) be a Rademacher sequence, i.e., a sequence of independent and identically distributed random variables satisfying P(ϵi=1)=P(ϵi=1)=1/2P(\epsilon_i=1)=P(\epsilon_i=-1)=1/2. Set Sn=a1ϵ1++anϵnS_n=a_1\epsilon_1+\cdots+a_n\epsilon_n for a=(a1,,an)Rna=(a_1,\dots,a_n)\in \mathbb{R}^n. The Hitczenko-Kwapien conjecture says that P(Sna)7/32P\left(\left|S_n\right|\geq\|a\|\right)\geq {7}/{32} for all aRna\in \mathbb{R}^n and nNn\in \mathbb{N}. Up to now, we know that it holds when n7n\leq 7. In this note, we show that it holds when n=8n=8.

Keywords

Cite

@article{arxiv.2310.14878,
  title  = {A note on the Hitczenko-Kwapien conjecture about a Rademacher sequence},
  author = {Shi-Zhen Liu and Ze-Yu Tao and Ze-Chun Hu},
  journal= {arXiv preprint arXiv:2310.14878},
  year   = {2023}
}

Comments

We knew that the problem has been solved by other persons