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arXiv · 2112.00950

Quantile Filtered Imitation Learning

David Brandfonbrener·William F. Whitney·Rajesh Ranganath·Joan Bruna
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Abstract

We introduce quantile filtered imitation learning (QFIL), a novel policy improvement operator designed for offline reinforcement learning. QFIL performs policy improvement by running imitation learning on a filtered version of the offline dataset. The filtering process removes $ s,a $ pairs whose estimated Q values fall below a given quantile of the pushforward distribution over values induced by sampling actions from the behavior policy. The definitions of both the pushforward Q distribution and resulting value function quantile are key contributions of our method. We prove that QFIL gives us a safe policy improvement step with function approximation and that the choice of quantile provides a natural hyperparameter to trade off bias and variance of the improvement step. Empirically, we perform a synthetic experiment illustrating how QFIL effectively makes a bias-variance tradeoff and we see that QFIL performs well on the D4RL benchmark.

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David Brandfonbrener, William F. Whitney, Rajesh Ranganath, Joan Bruna. 2021-12-02. Quantile Filtered Imitation Learning. https://arxiv.org/abs/2112.00950

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