A Case for Validation Buffer in Pessimistic Actor-Critic
Keywords: reinforcement learning, actor-critic, validation data
TL;DR: We analyse the approximation error in temporal difference and propose to use a small validation buffer in to adjust the pessimism of value updates in online RL
Abstract: In this paper, we investigate the issue of error accumulation in critic networks updated via pessimistic temporal difference objectives. We show that the critic approximation error can be approximated via a recursive fixed-point model similar to that of Bellman value. We use such recursive definition to retrieve the conditions under which the pessimistic critic is unbiased. Building on these insights, we propose Validation Pessimism Learning (VPL) algorithm. VPL uses a small validation buffer to adjust the levels of pessimism throughout the agent training, with the pessimism set such that the approximation error of the critic targets is minimized. We investigate the proposed approach on a variety of locomotion and manipulation tasks and report improvements in sample efficiency and performance.
Submission Number: 64
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