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arXiv 1802.04826stat.MLcs.LGstat.ME
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利用深度潜变量模型的精确似然性

Leveraging the Exact Likelihood of Deep Latent Variable Models

IT University of Copenhagen(哥本哈根信息技术大学)

Pierre-Alexandre Mattei, Jes Frellsen

摘要:

深度潜变量模型(DLVM)结合了深度神经网络的近似能力和生成模型的统计基础。变分方法通常用于推理;然而,这些模型的确切可能性在很大程度上被忽视了。这项工作的目的是研究这个量的一般性质,并说明如何在实践中利用它们。我们专注于重要的推理问题,依赖于可能性:估计和缺失数据插补。首先,我们研究了DLVMs的极大似然估计:特别是,我们证明了大多数用于连续数据的无约束模型具有无界的似然函数。这种有问题的行为被证明是模式崩溃的来源。我们还展示了如何确保最大似然估计的存在性,并与非参数混合模型建立了有用的联系。最后,我们描述了一个算法的缺失数据填补使用的深度潜变量模型的精确条件似然。在几个数据集上,我们的算法一致且显着优于用于DLVM的通常插补方案。

英文摘要:

Deep latent variable models (DLVMs) combine the approximation abilities of deep neural networks and the statistical foundations of generative models. Variational methods are commonly used for inference; however, the exact likelihood of these models has been largely overlooked. The purpose of this work is to study the general properties of this quantity and to show how they can be leveraged in practice. We focus on important inferential problems that rely on the likelihood: estimation and missing data imputation. First, we investigate maximum likelihood estimation for DLVMs: in particular, we show that most unconstrained models used for continuous data have an unbounded likelihood function. This problematic behaviour is demonstrated to be a source of mode collapse. We also show how to ensure the existence of maximum likelihood estimates, and draw useful connections with nonparametric mixture models. Finally, we describe an algorithm for missing data imputation using the exact conditional likelihood of a deep latent variable model. On several data sets, our algorithm consistently and significantly outperforms the usual imputation scheme used for DLVMs.

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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