arXiv:2409.04140stat.MLcs.LG2024-09被引 5

不用编码器的半变分自编码器,让隐变量直接优化解独立成分分析。

Half-VAE: An Encoder-Free VAE to Bypass Explicit Inverse Mapping

  • 去掉编码器,让隐变量作为可训练参数直接优化。
  • 在合适先验下,隐变量收敛时自然呈现相互独立特性。
  • 适合想避开反向映射、简化模型结构的研究者。

推断与逆问题密切相关,均涉及从观测数据中推导未知原因或参数。贝叶斯推断是一类强大方法,广泛用于因果推断等任务。变分推断是贝叶斯推断的子集,常用于高效近似复杂后验分布。变分自编码器(VAEs)结合变分推断与深度学习,已在多个领域广泛应用。本文探索了VAE在解决逆问题(如独立成分分析,ICA)中的潜力,无需依赖显式的逆映射过程。不同于其他基于VAE的ICA方法,该方法舍弃了VAE架构中的编码器,将隐变量设为可训练参数。即隐变量不再由编码器输出,而是通过目标函数直接优化以收敛到合适值。研究发现,在合适的先验设置下,隐变量作为可训练参数,在参数收敛时能表现出相互独立的性质,且完全无需编码过程。这一方法称为半变分自编码器(Half-VAE),通过移除编码器跳过逆映射过程。本研究证实了使用Half-VAE在无需显式逆映射的情况下求解ICA的可行性。

原文摘要 · Abstract (English)

Inference and inverse problems are closely related concepts, both fundamentally involving the deduction of unknown causes or parameters from observed data. Bayesian inference, a powerful class of methods, is often employed to solve a variety of problems, including those related to causal inference. Variational inference, a subset of Bayesian inference, is primarily used to efficiently approximate complex posterior distributions. Variational Autoencoders (VAEs), which combine variational inference with deep learning, have become widely applied across various domains. This study explores the potential of VAEs for solving inverse problems, such as Independent Component Analysis (ICA), without relying on an explicit inverse mapping process. Unlike other VAE-based ICA methods, this approach discards the encoder in the VAE architecture, directly setting the latent variables as trainable parameters. In other words, the latent variables are no longer outputs of the encoder but are instead optimized directly through the objective function to converge to appropriate values. We find that, with a suitable prior setup, the latent variables, represented by trainable parameters, can exhibit mutually independent properties as the parameters converge, all without the need for an encoding process. This approach, referred to as the Half-VAE, bypasses the inverse mapping process by eliminating the encoder. This study demonstrates the feasibility of using the Half-VAE to solve ICA without the need for an explicit inverse mapping process.

变分自编码器逆问题独立成分分析

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