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arXiv 2102.07699math.PRmath.CO
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无零区域随机变量的反集中

Anti-concentration of random variables from zero-free regions

Marcus Michelen, Julian Sahasrabudhe

摘要:

本文给出了随机变量的集中度与其概率母函数的根的分布之间的联系。令$X$是在$\{0,\ldots,n\}$中取值的随机变量,其中$X$具有$\mathbb{P}(X = 0)\mathbb{P}(X = n) > 0$和概率生成函数$f_X$。我们证明了如果$f_X$的所有零$ζ$满足$|\arg(ζ)| \geq δ$和$R^{-1} \leq |ζ| \leq R$,则\[ \operatorname{Var}(X) \geq c R^{-2π/δ}n, \],其中$c > 0$是一个绝对常数。我们表明,这一结果是尖锐的,高达$R$的指数中的因子$2$。因此,我们能够推导出不一定是独立同分布和的随机变量的Littlewood-Offord型定理。随机变量。

英文摘要:

This paper provides a connection between the concentration of a random variable and the distribution of the roots of its probability generating function. Let $X$ be a random variable taking values in $\{0,\ldots,n\}$ with $\mathbb{P}(X = 0)\mathbb{P}(X = n) > 0$ and with probability generating function $f_X$. We show that if all of the zeros $ζ$ of $f_X$ satisfy $|\arg(ζ)| \geq δ$ and $R^{-1} \leq |ζ| \leq R$ then \[ \operatorname{Var}(X) \geq c R^{-2π/δ}n, \] where $c > 0$ is a absolute constant. We show that this result is sharp, up to the factor $2$ in the exponent of $R$. As a consequence, we are able to deduce a Littlewood--Offord type theorem for random variables that are not necessarily sums of i.i.d.\ random variables.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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