论文标题

总体能量模型

Generalized Energy Based Models

论文作者

Arbel, Michael, Zhou, Liang, Gretton, Arthur

论文摘要

我们介绍了基于广义的能量模型(GEBM)进行生成建模。这些模型结合了两个训练有素的组件:基本分布(通常是隐式模型),可以在高维空间中学习具有较低固有维度的数据的支持;和能量函数,以完善学习支持的概率质量。能量函数和基础共同构成了最终模型,与GAN不同,GAN仅保留基本分布(“发电机”)。 GEBM是通过学习能量和基础之间交替进行培训的。我们表明,两个训练阶段都有明确的定义:通过最大程度地提高普遍的可能性来学习能量,而最终的基于能量的损失为学习基础提供了信息梯度。可以通过MCMC获得训练有素模型潜在空间的后部样品,从而在该空间中找到产生更好质量样品的区域。从经验上讲,关于图像生成任务的GEBM样本比单独学习的发电机的质量要好得多,这表明所有其他是相等的,GEBM将胜过相同复杂性的GAN。当使用归一化流程作为基础度量时,GEBMS在密度建模任务上取得了成功,将可比较的性能返回到同一网络的直接最大可能性。

We introduce the Generalized Energy Based Model (GEBM) for generative modelling. These models combine two trained components: a base distribution (generally an implicit model), which can learn the support of data with low intrinsic dimension in a high dimensional space; and an energy function, to refine the probability mass on the learned support. Both the energy function and base jointly constitute the final model, unlike GANs, which retain only the base distribution (the "generator"). GEBMs are trained by alternating between learning the energy and the base. We show that both training stages are well-defined: the energy is learned by maximising a generalized likelihood, and the resulting energy-based loss provides informative gradients for learning the base. Samples from the posterior on the latent space of the trained model can be obtained via MCMC, thus finding regions in this space that produce better quality samples. Empirically, the GEBM samples on image-generation tasks are of much better quality than those from the learned generator alone, indicating that all else being equal, the GEBM will outperform a GAN of the same complexity. When using normalizing flows as base measures, GEBMs succeed on density modelling tasks, returning comparable performance to direct maximum likelihood of the same networks.

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