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arXiv 0903.5136math.PRmath.CO
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有限平均度随机图的首次通过渗流

First passage percolation on random graphs with finite mean degrees

Shankar Bhamidi, Remco van der Hofstad, Gerard Hooghiemstra

摘要:

我们在组态模型上研究了第一通道渗流。假设每个边有一个独立的指数分布的边的权重,我们推导出显式的分布渐近网络中的两个随机选择的连接顶点之间的最小权重,以及最小权重路径上的边的数量,所谓的跳数。我们分析了度幂律指数为$τ>2$的组态模型,其中度假设为独立同分布。具有尾部分布,该尾部分布是具有指数$τ-1>1$的幂律形式,或者具有甚至更细的尾部($τ=\infty$)。在该模型中,度具有有限的一阶矩,而方差对于$τ>3$是有限的,但对于$τ\in(2,3)$是无限的。我们证明了一个中心极限定理的跳数,渐近相等的均值和方差等于$α\log{n}$,其中$α\in(0,1)$为$τ\in(2,3)$,而$α>1$为$τ>3$。这里$n$表示图的大小。对于$τ\in (2,3)$,已知两个随机选择的连接顶点之间的图形距离与$\log \log{n}$成比例[Electron. J. Probab. 12(2007)703- 766],也就是说,距离非常小。因此,边权重的增加导致网络几何结构的显著变化。我们进一步研究了最小权路径的权,并证明了适当中心化版本的分布收敛性。该研究继续了在[J.Math.Phys.49(2008)125218]中发起的程序,该程序表明$\log{n}$是i.i.d.下跳数的正确缩放。边缘无序,即使两个随机选择的顶点之间的图距离是小得多的顺序。在[ Extreme value theory,Poisson-Dirichlet distributions and first passage percolation on random networks(2009)Preprint]中研究了无限平均度($τ\in[1,2)$)的情况,其中证明了跳数保持一致有界并且在分布上收敛。

英文摘要:

We study first passage percolation on the configuration model. Assuming that each edge has an independent exponentially distributed edge weight, we derive explicit distributional asymptotics for the minimum weight between two randomly chosen connected vertices in the network, as well as for the number of edges on the least weight path, the so-called hopcount. We analyze the configuration model with degree power-law exponent $τ>2$, in which the degrees are assumed to be i.i.d. with a tail distribution which is either of power-law form with exponent $τ-1>1$, or has even thinner tails ($τ=\infty$). In this model, the degrees have a finite first moment, while the variance is finite for $τ>3$, but infinite for $τ\in(2,3)$. We prove a central limit theorem for the hopcount, with asymptotically equal means and variances equal to $α\log{n}$, where $α\in(0,1)$ for $τ\in(2,3)$, while $α>1$ for $τ>3$. Here $n$ denotes the size of the graph. For $τ\in (2,3)$, it is known that the graph distance between two randomly chosen connected vertices is proportional to $\log \log{n}$ [Electron. J. Probab. 12 (2007) 703--766], that is, distances are ultra small. Thus, the addition of edge weights causes a marked change in the geometry of the network. We further study the weight of the least weight path and prove convergence in distribution of an appropriately centered version. This study continues the program initiated in [J. Math. Phys. 49 (2008) 125218] of showing that $\log{n}$ is the correct scaling for the hopcount under i.i.d. edge disorder, even if the graph distance between two randomly chosen vertices is of much smaller order. The case of infinite mean degrees ($τ\in[1,2)$) is studied in [Extreme value theory, Poisson--Dirichlet distributions and first passage percolation on random networks (2009) Preprint] where it is proved that the hopcount remains uniformly bounded and converges in distribution.

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