Neural Spline Flows
This work addresses a bottleneck in normalizing flows for researchers and practitioners in machine learning, offering an incremental enhancement to existing methods.
The authors tackled the problem of limited flexibility in normalizing flows by proposing neural spline flows, which improved density estimation, variational inference, and generative modeling of images.
A normalizing flow models a complex probability density as an invertible transformation of a simple base density. Flows based on either coupling or autoregressive transforms both offer exact density evaluation and sampling, but rely on the parameterization of an easily invertible elementwise transformation, whose choice determines the flexibility of these models. Building upon recent work, we propose a fully-differentiable module based on monotonic rational-quadratic splines, which enhances the flexibility of both coupling and autoregressive transforms while retaining analytic invertibility. We demonstrate that neural spline flows improve density estimation, variational inference, and generative modeling of images.