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arXiv 2108.13992stat.MLcs.LG
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森林和树木图形模型的贝叶斯学习

Bayesian learning of forest and tree graphical models

University of Bristol(布里斯托大学)

Edmund Jones

摘要:

在高斯图模型结构的贝叶斯学习中,通常将注意力限制在某些类别的图上,并通过使用MCMC或诸如随机鸟枪搜索(SSS)的方法重复地从一个图移动到另一个图来近似后验分布。我给两个校正版本的算法不可分解的图形和讨论随机图形分布,特别是作为先验分布。本论文的主要研究课题是贝叶斯森林结构学习。限制对这些图的关注可以使用随机图上的定理来证明。我描述了如何使用Chow $\unicode{x2013}$ Liu算法和矩阵树定理来找到树上的MAP森林和后验分布中的某些量。我给适应版本的MCMC和SSS近似的后验分布的森林和树木,和系统存储这些图,以便很容易选择移动到相邻的图形。实验表明,当真实图是树或稀疏图时,带有树的SSS表现良好。在某些情况下,树或森林的SSS比可分解图的SSS更好。图先验改进了枢纽的检测,但需要大范围的概率。森林上的MCMC不能很好地混合,树木上的MCMC比SSS慢。(For更长的摘要见论文。)

英文摘要:

In Bayesian learning of Gaussian graphical model structure, it is common to restrict attention to certain classes of graphs and approximate the posterior distribution by repeatedly moving from one graph to another, using MCMC or methods such as stochastic shotgun search (SSS). I give two corrected versions of an algorithm for non-decomposable graphs and discuss random graph distributions, in particular as prior distributions. The main topic of the thesis is Bayesian structure-learning with forests or trees. Restricting attention to these graphs can be justified using theorems on random graphs. I describe how to use the Chow$\unicode{x2013}$Liu algorithm and the Matrix Tree Theorem to find the MAP forest and certain quantities in the posterior distribution on trees. I give adapted versions of MCMC and SSS for approximating the posterior distribution for forests and trees, and systems for storing these graphs so that it is easy to choose moves to neighbouring graphs. Experiments show that SSS with trees does well when the true graph is a tree or sparse graph. SSS with trees or forests does better than SSS with decomposable graphs in certain cases. Graph priors improve detection of hubs but need large ranges of probabilities. MCMC on forests fails to mix well and MCMC on trees is slower than SSS. (For a longer abstract see the thesis.)

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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