论文标题

蒙特卡洛目标的共同信息约束

Mutual Information Constraints for Monte-Carlo Objectives

论文作者

Melis, Gábor, György, András, Blunsom, Phil

论文摘要

训练为变异自动编码器训练的密度模型的常见故障模式是在不依赖其潜在变量的情况下对数据进行建模,从而使这些变量毫无用处。在文献中已经分别研究了两个促成因素,即模型的指定和变异下限的松弛。我们将这两条研究编织在一起,特别是蒙特 - 卡洛目标的更严格的界限以及对观察变量和潜在变量之间相互信息的约束。将共同信息估计为易于使用的变分后$ q(z | x)$之间的平均kullback-leibler差异,而先前则不适用于蒙特 - 卡洛目标,因为$ q(z | x)$不再是该模型的真实后验$ p(z | x)$的直接近似。因此,我们通过回收物镜中使用的样本来构建真实后部的kullback-leibler差异的估计量,我们使用该样品训练连续和离散潜伏期的模型,以大大改善的速率延伸,没有后部倒塌。在缓解的同时,对数据建模和使用潜伏期之间的权衡仍然存在,我们敦促评估一系列相互信息值的推理方法。

A common failure mode of density models trained as variational autoencoders is to model the data without relying on their latent variables, rendering these variables useless. Two contributing factors, the underspecification of the model and the looseness of the variational lower bound, have been studied separately in the literature. We weave these two strands of research together, specifically the tighter bounds of Monte-Carlo objectives and constraints on the mutual information between the observable and the latent variables. Estimating the mutual information as the average Kullback-Leibler divergence between the easily available variational posterior $q(z|x)$ and the prior does not work with Monte-Carlo objectives because $q(z|x)$ is no longer a direct approximation to the model's true posterior $p(z|x)$. Hence, we construct estimators of the Kullback-Leibler divergence of the true posterior from the prior by recycling samples used in the objective, with which we train models of continuous and discrete latents at much improved rate-distortion and no posterior collapse. While alleviated, the tradeoff between modelling the data and using the latents still remains, and we urge for evaluating inference methods across a range of mutual information values.

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