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Fourier Policy Gradients (arxiv.org)
2 points by adamnemecek on May 3, 2019 | hide | past | pdf | discuss on HN

In plain words: It rewrites the integrals in policy gradients as multiplications using wave math, so updates can be solved exactly instead of guessed from samples. This keeps the low-variance benefit of exact expected gradients for many policy and critic types, where sampling works only in narrow cases.

Abstract

We propose a new way of deriving policy gradient updates for reinforcement learning. Our technique, based on Fourier analysis, recasts integrals that arise with expected policy gradients as convolutions and turns them into multiplications. The obtained analytical solutions allow us to capture the low variance benefits of EPG in a broad range of settings. For the critic, we treat trigonometric and radial basis functions, two function families with the universal approximation property. The choice of policy can be almost arbitrary, including mixtures or hybrid continuous-discrete probability distributions. Moreover, we derive a general family of sample-based estimators for stochastic policy gradients, which unifies existing results on sample-based approximation. We believe that this technique has the potential to shape the next generation of policy gradient approaches, powered by analytical results.

Matthew Fellows, Kamil Ciosek, Shimon Whiteson
arXiv:1802.06891 · cs.LG, cs.AI · submitted Feb 19, 2018 · updated May 30, 2018
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