Soft-Constrained Optimization of Latent Space in Variational Autoencoders

精选理由

想提升VAE解纠缠又不想牺牲重建质量?这篇论文用软约束同时搞定,dSprites上FactorVAE得分刷到0.891,值得看看。

AI 摘要

本文提出软约束优化方法以平衡VAE的编码容量与解纠缠。在dSprites数据集上,熵约束(EC)使聚合潜在变量激活得分提升43%-62%,FactorVAE得分达0.891(对比β-VAE变体的0.847),重建误差降低38%。在MNIST上,权重过滤将下游分类器所用潜在维度从10降至2,精度保持在90%以上且收敛轮次减少37%。研究发现,低熵离散因子倾向于合并到单个潜在变量,高熵连续因子则分散到多个变量中。

原文 · arXiv cs.LG

The usefulness of a variational autoencoder (VAE) depends on two properties of its latent space that are hard to obtain together: high encoding capacity in the individual latent variables, and a low-dimensional, disentangled organization of those variables. Weakening the Kullback-Leibler regularization raises capacity but degrades disentanglement, while strengthening it prunes latent variables away entirely. We formulate VAE training as a soft-constrained optimization problem that addresses both. First, we impose an entropy-based constraint (EC) on individual latent variables, showing that the entropy of a latent code upper-bounds the mutual information it carries about the generative factors of the data. Second, we propose a weight-filter method that exploits the slack of the soft constraint to prune low-entropy dimensions during downstream training. On dSprites, the EC raises the aggregate latent-variable activation score by 43-62% over a vanilla VAE, attains the highest FactorVAE score among the \b{eta} \b{eta}-VAE variants (0.891 vs 0.847), and lowers reconstruction error by up to 38%. On MNIST, the weight filter reduces the latent dimensionality supplied to a downstream classifier from ten to two while holding accuracy above 90%, converging in 37% fewer epochs than the same procedure without the EC. We also find that low-entropy discrete factors tend to merge into a single latent variable, whereas high-entropy continuous factors are distributed across several.