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Main Authors: Tavakoli, Arash, Ghiassian, Sina, Rakićević, Nemanja
Format: Preprint
Published: 2024
Subjects:
Online Access:https://arxiv.org/abs/2410.06317
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author Tavakoli, Arash
Ghiassian, Sina
Rakićević, Nemanja
author_facet Tavakoli, Arash
Ghiassian, Sina
Rakićević, Nemanja
contents While conventional wisdom holds that policy gradient methods are better suited to complex action spaces than action-value methods, foundational work has shown that the two paradigms are equivalent in small, finite action spaces (O'Donoghue et al., 2017; Schulman et al., 2017a). This raises the question of why their computational applicability and performance diverge as the complexity of the action space increases. We hypothesize that the apparent superiority of policy gradients in such settings stems not from intrinsic qualities of the paradigm but from universal principles that can also be applied to action-value methods, enabling similar functions. We identify three such principles and provide a framework for incorporating them into action-value methods. To support our hypothesis, we instantiate this framework in what we term QMLE, for Q-learning with maximum likelihood estimation. Our results show that QMLE can be applied to complex action spaces at a computational cost comparable to that of policy gradient methods, all without using policy gradients. Furthermore, QMLE exhibits strong performance on the DeepMind Control Suite, even when compared to state-of-the-art methods such as DMPO and D4PG.
format Preprint
id arxiv_https___arxiv_org_abs_2410_06317
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Learning in complex action spaces without policy gradients
Tavakoli, Arash
Ghiassian, Sina
Rakićević, Nemanja
Machine Learning
Artificial Intelligence
While conventional wisdom holds that policy gradient methods are better suited to complex action spaces than action-value methods, foundational work has shown that the two paradigms are equivalent in small, finite action spaces (O'Donoghue et al., 2017; Schulman et al., 2017a). This raises the question of why their computational applicability and performance diverge as the complexity of the action space increases. We hypothesize that the apparent superiority of policy gradients in such settings stems not from intrinsic qualities of the paradigm but from universal principles that can also be applied to action-value methods, enabling similar functions. We identify three such principles and provide a framework for incorporating them into action-value methods. To support our hypothesis, we instantiate this framework in what we term QMLE, for Q-learning with maximum likelihood estimation. Our results show that QMLE can be applied to complex action spaces at a computational cost comparable to that of policy gradient methods, all without using policy gradients. Furthermore, QMLE exhibits strong performance on the DeepMind Control Suite, even when compared to state-of-the-art methods such as DMPO and D4PG.
title Learning in complex action spaces without policy gradients
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2410.06317