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arXiv 1202.3071math.PR
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度为重尾的随机图的度-度相关性

Degree-degree correlations in random graphs with heavy-tailed degrees

Nelly Litvak, Remco van der Hofstad

摘要:

混合模式在大型自组织网络,如互联网,万维网,社会和生物网络的特点往往是度度{依赖}之间的相邻节点。常用的皮尔逊相关系数(称为扩散系数)的问题之一是{在扩散网络中,其大小随着网络大小而减小}。这使得不可能比较混合模式,例如,在两个不同大小的Web抓取中。我们从两个重尾高度相关的随机变量$X$和$Y$的简单模型开始,证明了样本相关系数在分布上要么收敛于$[-1,1]$上的一个适当的随机变量,要么收敛于零,并且如果$X,Y\ge 0$,则极限是非负的.接下来我们证明,当度分布具有无限个三阶矩时,在大图极限中它是非负的。我们认为替代度度依赖措施,斯皮尔曼的ρ的基础上,并证明它收敛到一个适当的限制在非常一般的条件下。我们验证了这些条件在常见的网络模型,如配置模型和偏好依恋模型。我们的结论是,秩相关性提供了一个合适的和翔实的方法来揭示网络混合模式。

英文摘要:

Mixing patterns in large self-organizing networks, such as the Internet, the World Wide Web, social and biological networks are often characterized by degree-degree {dependencies} between neighbouring nodes. One of the problems with the commonly used Pearson's correlation coefficient (termed as the assortativity coefficient) is that {in disassortative networks its magnitude decreases} with the network size. This makes it impossible to compare mixing patterns, for example, in two web crawls of different size. We start with a simple model of two heavy-tailed highly correlated random variable $X$ and $Y$, and show that the sample correlation coefficient converges in distribution either to a proper random variable on $[-1,1]$, or to zero, and if $X,Y\ge 0$ then the limit is non-negative. We next show that it is non-negative in the large graph limit when the degree distribution has an infinite third moment. We consider the alternative degree-degree dependency measure, based on the Spearman's rho, and prove that it converges to an appropriate limit under very general conditions. We verify that these conditions hold in common network models, such as configuration model and Preferential Attachment model. We conclude that rank correlations provide a suitable and informative method for uncovering network mixing patterns.

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