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Main Authors: Landers, Matthew, Killian, Taylor W., Hartvigsen, Thomas, Doryab, Afsaneh
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2601.04441
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author Landers, Matthew
Killian, Taylor W.
Hartvigsen, Thomas
Doryab, Afsaneh
author_facet Landers, Matthew
Killian, Taylor W.
Hartvigsen, Thomas
Doryab, Afsaneh
contents Reinforcement learning in discrete combinatorial action spaces requires searching over exponentially many joint actions to simultaneously select multiple sub-actions that form coherent combinations. Existing approaches either simplify policy learning by assuming independence across sub-actions, which often yields incoherent or invalid actions, or attempt to learn action structure and control jointly, which is slow and unstable. We introduce Structured Policy Initialization (SPIN), a two-stage framework that first pre-trains an Action Structure Model (ASM) to capture the manifold of valid actions, then freezes this representation and trains lightweight policy heads for control. On challenging discrete DM Control benchmarks, SPIN improves average return by up to 39% over the state of the art while reducing time to convergence by up to 12.8$\times$.
format Preprint
id arxiv_https___arxiv_org_abs_2601_04441
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Improving and Accelerating Offline RL in Large Discrete Action Spaces with Structured Policy Initialization
Landers, Matthew
Killian, Taylor W.
Hartvigsen, Thomas
Doryab, Afsaneh
Machine Learning
Reinforcement learning in discrete combinatorial action spaces requires searching over exponentially many joint actions to simultaneously select multiple sub-actions that form coherent combinations. Existing approaches either simplify policy learning by assuming independence across sub-actions, which often yields incoherent or invalid actions, or attempt to learn action structure and control jointly, which is slow and unstable. We introduce Structured Policy Initialization (SPIN), a two-stage framework that first pre-trains an Action Structure Model (ASM) to capture the manifold of valid actions, then freezes this representation and trains lightweight policy heads for control. On challenging discrete DM Control benchmarks, SPIN improves average return by up to 39% over the state of the art while reducing time to convergence by up to 12.8$\times$.
title Improving and Accelerating Offline RL in Large Discrete Action Spaces with Structured Policy Initialization
topic Machine Learning
url https://arxiv.org/abs/2601.04441