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arXiv 0903.2906math.PR
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一般图上Ising-Gibbs采样器的精确阈值

Exact thresholds for Ising-Gibbs samplers on general graphs

Elchanan Mossel, Allan Sly

摘要:

我们建立严格的结果快速混合吉布斯采样的铁磁伊辛模型一般图。我们证明了如果\[(d-1)\tanhβ<1,\],则存在一个常数C,使得在任意n个顶点和最大度d的图上的铁磁伊辛模型的Gibbs采样器的离散时间混合时间,其中所有的相互作用都以$β$为界,任意的外场都以$Cn\log n$为界.此外,谱间隙是一致有界远离0的所有这样的图,以及无限图的最大程度的d。我们进一步表明,当$d\tanhβ<1$,具有高概率超过埃尔多斯-雷尼随机图$G(n,d/n)$,它认为吉布斯采样器的混合时间是\[n^{1+Θ({1}/{\log\log n})}.\]这两个结果是紧密的,因为它是已知的随机规则和埃尔多斯-雷尼随机图的混合时间是,具有高概率,指数n时,$(d-1)\tanhβ>1$,和$d\tanhβ>1$,分别。据我们所知,我们的结果给出了一般图上自旋系统快速混合的第一个紧充分条件。此外,我们的研究结果是第一个严格的结果建立精确的阈值动态随机图的空间阈值树。

英文摘要:

We establish tight results for rapid mixing of Gibbs samplers for the Ferromagnetic Ising model on general graphs. We show that if \[(d-1)\tanhβ<1,\] then there exists a constant C such that the discrete time mixing time of Gibbs samplers for the ferromagnetic Ising model on any graph of n vertices and maximal degree d, where all interactions are bounded by $β$, and arbitrary external fields are bounded by $Cn\log n$. Moreover, the spectral gap is uniformly bounded away from 0 for all such graphs, as well as for infinite graphs of maximal degree d. We further show that when $d\tanhβ<1$, with high probability over the Erdos-Renyi random graph $G(n,d/n)$, it holds that the mixing time of Gibbs samplers is \[n^{1+Θ({1}/{\log\log n})}.\] Both results are tight, as it is known that the mixing time for random regular and Erdos-Renyi random graphs is, with high probability, exponential in n when $(d-1)\tanhβ>1$, and $d\tanhβ>1$, respectively. To our knowledge our results give the first tight sufficient conditions for rapid mixing of spin systems on general graphs. Moreover, our results are the first rigorous results establishing exact thresholds for dynamics on random graphs in terms of spatial thresholds on trees.

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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