A Generalised Linear Model Framework for Variational Autoencoders based on Exponential Dispersion Families

Although variational autoencoders (VAE) are successfully used to obtain meaningful low-dimensional representations for high-dimensional data, aspects of their loss function are not yet fully understood. We introduce a theoretical framework that is based on a connection between VAE and generalized linear models (GLM). The equality between the activation function of a VAE and the inverse of the link function of a GLM enables us to provide a systematic generalization of the loss analysis for VAE based on the assumption that the distribution of the decoder belongs to an exponential dispersion family (EDF). As a further result, we can initialize VAE nets by maximum likelihood estimates (MLE) that enhance the training performance on both synthetic and real world data sets.

A lower bound for the ELBO of the Bernoulli Variational Autoencoder

We consider a variational autoencoder (VAE) for binary data. Our main innovations are an interpretable lower bound for its training objective, a modified initialization and architecture of such a VAE that leads to faster training, and a decision support for finding the appropriate dimension of the latent space via using a PCA. Numerical examples illustrate our theoretical result and the performance of the new architecture.