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arXiv 1301.0563cs.LGcs.AIstat.ML
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插值条件密度树

Interpolating Conditional Density Trees

Carnegie Mellon University(卡内基梅隆大学)

Scott Davies, Andrew Moore

摘要:

许多变量的联合分布通常通过将它们分解为更简单,更低维的条件分布的乘积来建模,例如在稀疏连接的贝叶斯网络中。然而,当存在许多数据点和具有复杂非线性关系的许多连续变量时,特别是当没有分解联合分布的好方法时,自动学习这样的模型在计算上可能非常昂贵。在这种情况下,以前的研究一般集中在使用离散化技术,其中每个连续变量都有一个单独的离散化,用于整个网络。在本文中,我们提出并比较了各种各样的基于树的算法学习和评估连续变量上的条件密度估计。这些树可以被认为是离散化,根据特定的相互作用建模,但是,在一个给定的树叶的树的密度不需要假设恒定的,我们表明,这种不均匀的叶密度导致更准确的密度估计。我们已经开发了贝叶斯网络结构-学习算法,采用这些基于树的条件密度表示,我们表明,它们可以用来实际学习复杂的联合概率模型超过几十个连续变量从数千个数据点。我们专注于寻找同时准确,快速学习和快速评估的模型。

英文摘要:

Joint distributions over many variables are frequently modeled by decomposing them into products of simpler, lower-dimensional conditional distributions, such as in sparsely connected Bayesian networks. However, automatically learning such models can be very computationally expensive when there are many datapoints and many continuous variables with complex nonlinear relationships, particularly when no good ways of decomposing the joint distribution are known a priori. In such situations, previous research has generally focused on the use of discretization techniques in which each continuous variable has a single discretization that is used throughout the entire network. \ In this paper, we present and compare a wide variety of tree-based algorithms for learning and evaluating conditional density estimates over continuous variables. These trees can be thought of as discretizations that vary according to the particular interactions being modeled; however, the density within a given leaf of the tree need not be assumed constant, and we show that such nonuniform leaf densities lead to more accurate density estimation. We have developed Bayesian network structure-learning algorithms that employ these tree-based conditional density representations, and we show that they can be used to practically learn complex joint probability models over dozens of continuous variables from thousands of datapoints. We focus on finding models that are simultaneously accurate, fast to learn, and fast to evaluate once they are learned.

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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