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arXiv 1104.4460math.GRmath.MG
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群的统计双曲性

Statistical hyperbolicity in groups

Moon Duchin, Samuel Lelièvre, Christopher Mooney

摘要:

在本文中,我们介绍了一个几何统计称为“蔓延”的一组相对于一个发电机组,基于平均距离的字度量之间的字对长度相等。这种蔓延量化了对双曲线的某种阻碍。具有最大蔓延的组演示文稿(即,没有这个障碍)被称为统计双曲线。我们首先蔓延曲率和非初等双曲群是统计双曲,然后给出一些结果的产品,迪斯特尔领导人图和lampighter组。在自由阿尔贝群中,字度量渐近地逼近由凸多胞体导出的范数,使得对蔓延的研究归结为凸几何中的问题。我们提出了一个算法,计算蔓延准确地为任何发电机组,从而量化失败的各种介绍Z^d是双曲线。这导致了一个关于极值的猜想,与经典的马勒猜想有关。

英文摘要:

In this paper, we introduce a geometric statistic called the "sprawl" of a group with respect to a generating set, based on the average distance in the word metric between pairs of words of equal length. The sprawl quantifies a certain obstruction to hyperbolicity. Group presentations with maximum sprawl (i.e., without this obstruction) are called statistically hyperbolic. We first relate sprawl to curvature and show that nonelementary hyperbolic groups are statistically hyperbolic, then give some results for products, for Diestel-Leader graphs and lamplighter groups. In free abelian groups, the word metrics asymptotically approach norms induced by convex polytopes, causing the study of sprawl to reduce to a problem in convex geometry. We present an algorithm that computes sprawl exactly for any generating set, thus quantifying the failure of various presentations of Z^d to be hyperbolic. This leads to a conjecture about the extreme values, with a connection to the classic Mahler conjecture.

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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