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Learning to Draw Samples with Amortized Stein Variational Gradient Descent
Proceedings of the 33rd Conference on Uncertainty in Artificial Intelligence, PMLR R15:521-530, 2017.
Abstract
We propose a simple algorithm to train stochas- tic neural networks to draw samples from given target distributions for probabilistic inference. Our method is based on iteratively adjusting the neural network parameters so that the output changes along a Stein variational gradient di- rection (Liu & Wang, 2016) that maximally de- creases the KL divergence with the target distri- bution. Our method works for any target dis- tribution specified by their unnormalized density function, and can train any black-box architec- tures that are differentiable in terms of the pa- rameters we want to adapt. We demonstrate our method with a number of applications, including variational autoencoder (VAE) with expressive encoders to model complex latent space struc- tures, and hyper-parameter learning of MCMC samplers that allows Bayesian inference to adap- tively improve itself when seeing more data.