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arXiv 1106.4864cs.AI
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概率推理中语境独立性的利用

Exploiting Contextual Independence In Probabilistic Inference

University of British Columbia(英属哥伦比亚大学);Hong Kong University of Science and Technology(香港科技大学)

D. Poole, N. L. Zhang

摘要:

贝叶斯信念网络已经变得突出,因为它们为概率推理适用的许多问题提供了紧凑的表示,并且有算法可以利用这种紧凑性。下一步是允许一个变量的条件概率的紧凑表示,给定它的父母。在本文中,我们提出了这样一种表示,利用上下文的独立性,在父母的背景下,哪些变量作为父母可能取决于其他变量的值。内部表示是根据上下文因素(confactors),即上下文和表的一对。上下文变量消除算法基于标准变量消除算法,依次消除非查询变量,但在消除变量时,需要相乘的表可以取决于上下文。当没有上下文无关结构可供利用时,该算法简化为标准变量消除。我们展示了如何可以更有效地比变量消除时,有结构利用。我们解释了为什么这种新方法可以利用更多的结构比以前的方法结构化的信念网络推理和类似的算法,使用树。

英文摘要:

Bayesian belief networks have grown to prominence because they provide compact representations for many problems for which probabilistic inference is appropriate, and there are algorithms to exploit this compactness. The next step is to allow compact representations of the conditional probabilities of a variable given its parents. In this paper we present such a representation that exploits contextual independence in terms of parent contexts; which variables act as parents may depend on the value of other variables. The internal representation is in terms of contextual factors (confactors) that is simply a pair of a context and a table. The algorithm, contextual variable elimination, is based on the standard variable elimination algorithm that eliminates the non-query variables in turn, but when eliminating a variable, the tables that need to be multiplied can depend on the context. This algorithm reduces to standard variable elimination when there is no contextual independence structure to exploit. We show how this can be much more efficient than variable elimination when there is structure to exploit. We explain why this new method can exploit more structure than previous methods for structured belief network inference and an analogous algorithm that uses 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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