Behind the Myth of Exploration in Policy Gradients

20 Sept 2023 (modified: 11 Feb 2024)Submitted to ICLR 2024EveryoneRevisionsBibTeX
Primary Area: reinforcement learning
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Keywords: Reinforcement Learning, Policy Gradients, Exploration, Optimization
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TL;DR: Novel analysis and interpretations of exploration strategies used in policy-gradient methods in reinforcement learning by considering them from an optimization perspective.
Abstract: Policy-gradient algorithms are effective reinforcement learning methods for solving control problems with continuous state and action spaces. To compute near-optimal policies, it is essential in practice to include exploration terms in the learning objective. Although the effectiveness of these terms is usually justified by an intrinsic need to explore environments, we propose a novel analysis and distinguish two different implications of these techniques. First, they enable a smooth learning objective and eliminate local optima while preserving the global maximum. Second, they modify the gradient estimates, increasing the probability that the stochastic parameter update eventually provides an optimal policy. In light of these effects, we discuss and illustrate empirically exploration strategies based on entropy bonuses, highlighting their limitations and opening avenues for future works in the design and analysis of such strategies.
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Submission Number: 2823
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