arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2001.01467math.PRmath.COmath.GR

顶点传递图中体积增长、等周性与逃逸概率之间的尖锐关系

Sharp relations between volume growth, isoperimetry and escape probability in vertex-transitive graphs

Romain Tessera, Matthew Tointon

AI总结:

本文在顶点传递图中建立了体积增长、等周性与随机游走逃逸概率之间的尖锐定量关系,给出了 Varopoulos 定理的有限性精细化,并证实了 Benjamini-Kozma 猜想及相关局部性结果。

摘要:

我们证明了顶点传递图上的简单随机游走在返回起点之前逃出半径为 $r$ 的球的概率的尖锐界。特别地,这表明如果半径为 $r$ 的球的大小略大于 $r$ 的二次方,那么这个概率有下界。另一方面,我们证明如果半径为 $r$ 的球的体积略小于 $r$ 的三次方,那么对于所有更大的球,这个概率按对数衰减。这些结果代表了 Varopoulos 定理的一个有限性精细化:顶点传递图上的随机游走是常返的当且仅当该图至多具有二次体积增长。它们还蕴含逃逸概率在 $0$ 处存在间隙:存在一个普适常数 $c>0$,使得任意顶点传递图上的随机游走要么是常返的,要么具有至少为 $c$ 的逃逸到无穷远的概率。我们还证明了这些结果在有限图上的版本,特别地证实并加强了 Benjamini 和 Kozma 在 2002 年提出的一个猜想。此外,我们还将结果推广,给出了 $p$-抛物顶点传递图特征的尖锐有限性版本,证明了顶点传递图的一系列尖锐等周不等式,并证明了顶点传递图上随机游走逃逸概率的局部性结果,该结果可视为 Schramm 关于临界渗流概率的局部性猜想的类似物。

英文摘要:

We prove sharp bounds on the probability that the simple random walk on a vertex-transitive graph escapes the ball of radius $r$ before returning to its starting point. In particular, this shows that if the ball of radius $r$ has size slightly greater than quadratic in $r$ then this probability is bounded from below. On the other hand, we show that if the ball of radius $r$ has volume slightly less than cubic in $r$ then this probability decays logarithmically for all larger balls. These results represent a finitary refinement of Varopoulos's theorem that a random walk on a vertex-transitive graph is recurrent if and only if the graph has at most quadratic volume growth. They also imply the existence of a gap at $0$ for escape probabilities: there exists a universal constant $c>0$ such that the random walk on an arbitrary vertex-transitive graph is either recurrent or has a probability of at least $c$ of escaping to infinity. We also prove versions of these results for finite graphs, in particular confirming and strengthening a conjecture of Benjamini and Kozma from 2002. Amongst other things, we also generalise our results to give a sharp finitary version of the characterisation of $p$-parabolic vertex-transitive graphs, prove a number of sharp isoperimetric inequalities for vertex-transitive graphs, and prove a locality result for the escape probability of the random walk on a vertex-transitive graph that can be seen as an analogue of Schramm's locality conjecture for the critical percolation probability.

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。

↑