A limit result for self-normalized random sums

被引:0
|
作者
Zhang Li-xin
Wen Ji-wei
机构
[1] Zhejiang University,Department of Mathematics
来源
关键词
self-normalized; i.i.d. random variables; Chernoff function; A; O211.4;
D O I
10.1631/BF02841181
中图分类号
学科分类号
摘要
Suppose {X, Xn;n≥1} is a sequence i.i.d.r.v. withEX=0 andEX2<∞. Shao (1995) proved a conjecture of Révész (1990); ifP(X=±1)=1/2, then\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$\mathop {lim}\limits_{n \to \infty } \mathop {max}\limits_{0 \leqslant j< n} \mathop {max}\limits_{1 \leqslant k \leqslant n - j} \frac{{\sum\limits_{i = j + 1}^{i = j + k} {X_i } }}{{(2klogn)^{1/2} }} = 1 a. s.$$ \end{document}. Furthermore he conjectured that\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$1 \leqslant \mathop {lim}\limits_{n \to \infty } \mathop {max}\limits_{0 \leqslant j< n} \mathop {max}\limits_{1 \leqslant k \leqslant n - j} \frac{{\sum\limits_{i = j + 1}^{i = j + k} {X_i } }}{{\{ \sum\limits_{i = j + 1}^{i = j + k} {X_i^2 (2klogn)} \} ^{1/2} }} = {\rm K}< \infty a. s.$$ \end{document}. In this paper we prove that if\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$\mathop {sup}\limits_{b > 0} P(X = b) \geqslant P(X = 0)$$ \end{document} then this conjecture is ture.
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页码:79 / 83
页数:4
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