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arXiv 1706.06968math.PR
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Polish群上随机游动的精确耦合

Exact Coupling of Random Walks on Polish Groups

James T. Murphy

摘要:

研究了随机游动的精确耦合问题。允许一个成功的精确耦合的条件是必要的,在阿贝尔的情况下也是充分的。在阿贝尔的情况下,它表明,一个随机游走$S$与步长分布$μ$开始于$0$承认一个成功的精确耦合与一个版本$S^x$开始于$x$当且仅当有$n\geq 1$与$μ^{n} \wedge μ^{n}(x+\cdot) \neq 0$。此外,当存在一个成功的精确耦合时,如果$x$具有无限阶,则$S_n$和$S^x_n$之间的总变化距离被确定为$O(n^{-1/2})$,如果$x$具有有限阶,则对于某些$ρ\in (0,1)$,$O(ρ^n)$。特别地,本文解决了H. Thorisson在$\mathbb{R}$上成功地精确耦合了随机游动。还应注意,可以构造成功的精确耦合的这种$x$的集合是Borel可测群。最后,研究了可能精确耦合的弱概念及其与成功精确耦合的关系。

英文摘要:

Exact coupling of random walks is studied. Conditions for admitting a successful exact coupling are given that are necessary and in the Abelian case also sufficient. In the Abelian case, it is shown that a random walk $S$ with step-length distribution $μ$ started at $0$ admits a successful exact coupling with a version $S^x$ started at $x$ if and only if there is $n\geq 1$ with $μ^{n} \wedge μ^{n}(x+\cdot) \neq 0$. Moreover, when a successful exact coupling exists, the total variation distance between $S_n$ and $S^x_n$ is determined to be $O(n^{-1/2})$ if $x$ has infinite order, or $O(ρ^n)$ for some $ρ\in (0,1)$ if $x$ has finite order. In particular, this paper solves a problem posed by H. Thorisson on successful exact coupling of random walks on $\mathbb{R}$. It is also noted that the set of such $x$ for which a successful exact coupling can be constructed is a Borel measurable group. Lastly, the weaker notion of possible exact coupling and its relationship to successful exact coupling are studied.

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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