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arXiv 1408.1809math.STstat.OTstat.TH
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贝叶斯网络的边界图

Graphs for margins of Bayesian networks

Robin J. Evans

摘要:

有向无圈图(DAG)模型,也称为贝叶斯网络,对多元概率分布施加条件独立约束,广泛应用于概率推理、机器学习和因果推理中。如果潜变量包含在这样的模型中,那么剩余(观察到的)变量上的可能边缘分布的集合通常是复杂的,并且不由任何DAG表示。为了克服这一点,已经引入了使用重边类型的更大类的混合图形模型;然而,这些类并不代表可以作为DAG的边缘出现的所有模型。在本文中,我们表明,这是因为普通的混合图从根本上是不够丰富,以捕捉各种边际模型。我们引入了一类新的超图,称为mDAG,和一个潜在的投影操作,以获得从边缘的DAG的mDAG。我们表明,每个不同的边缘的DAG模型表示至少有一个mDAG,并提供图形化的结果对表征时,两个这样的边缘模型是相同的。最后,我们表明,mDAGs正确地捕获的边际结构的因果解释DAGs下的干预观察变量。

英文摘要:

Directed acyclic graph (DAG) models, also called Bayesian networks, impose conditional independence constraints on a multivariate probability distribution, and are widely used in probabilistic reasoning, machine learning and causal inference. If latent variables are included in such a model, then the set of possible marginal distributions over the remaining (observed) variables is generally complex, and not represented by any DAG. Larger classes of mixed graphical models, which use multiple edge types, have been introduced to overcome this; however, these classes do not represent all the models which can arise as margins of DAGs. In this paper we show that this is because ordinary mixed graphs are fundamentally insufficiently rich to capture the variety of marginal models. We introduce a new class of hyper-graphs, called mDAGs, and a latent projection operation to obtain an mDAG from the margin of a DAG. We show that each distinct marginal of a DAG model is represented by at least one mDAG, and provide graphical results towards characterizing when two such marginal models are the same. Finally we show that mDAGs correctly capture the marginal structure of causally-interpreted DAGs under interventions on the observed variables.

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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