Abstract
We present a new method for evaluating and training unnormalized density
models. Our approach only requires access to the gradient of the unnormalized
model's log-density. We estimate the Stein discrepancy between the data density
p(x) and the model density q(x) defined by a vector function of the data. We
parameterize this function with a neural network and fit its parameters to
maximize the discrepancy. This yields a novel goodness-of-fit test which
outperforms existing methods on high dimensional data. Furthermore, optimizing
$q(x)$ to minimize this discrepancy produces a novel method for training
unnormalized models which scales more gracefully than existing methods. The
ability to both learn and compare models is a unique feature of the proposed
method.
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