Partially Equivariant Reinforcement Learning in Symmetry-Breaking Environments

Fuente: arXiv
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Autori principali: Chang, Junwoo, Park, Minwoo, Seo, Joohwan, Horowitz, Roberto, Lee, Jongmin, Choi, Jongeun
Natura: Preprint
Pubblicazione: 2025
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author Chang, Junwoo
Park, Minwoo
Seo, Joohwan
Horowitz, Roberto
Lee, Jongmin
Choi, Jongeun
author_facet Chang, Junwoo
Park, Minwoo
Seo, Joohwan
Horowitz, Roberto
Lee, Jongmin
Choi, Jongeun
contents Group symmetries provide a powerful inductive bias for reinforcement learning (RL), enabling efficient generalization across symmetric states and actions via group-invariant Markov Decision Processes (MDPs). However, real-world environments almost never realize fully group-invariant MDPs; dynamics, actuation limits, and reward design usually break symmetries, often only locally. Under group-invariant Bellman backups for such cases, local symmetry-breaking introduces errors that propagate across the entire state-action space, resulting in global value estimation errors. To address this, we introduce Partially group-Invariant MDP (PI-MDP), which selectively applies group-invariant or standard Bellman backups depending on where symmetry holds. This framework mitigates error propagation from locally broken symmetries while maintaining the benefits of equivariance, thereby enhancing sample efficiency and generalizability. Building on this framework, we present practical RL algorithms -- Partially Equivariant (PE)-DQN for discrete control and PE-SAC for continuous control -- that combine the benefits of equivariance with robustness to symmetry-breaking. Experiments across Grid-World, locomotion, and manipulation benchmarks demonstrate that PE-DQN and PE-SAC significantly outperform baselines, highlighting the importance of selective symmetry exploitation for robust and sample-efficient RL. Project page: https://pranaboy72.github.io/perl_page/
format Preprint
id arxiv_https___arxiv_org_abs_2512_00915
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Partially Equivariant Reinforcement Learning in Symmetry-Breaking Environments
Chang, Junwoo
Park, Minwoo
Seo, Joohwan
Horowitz, Roberto
Lee, Jongmin
Choi, Jongeun
Machine Learning
Robotics
Group symmetries provide a powerful inductive bias for reinforcement learning (RL), enabling efficient generalization across symmetric states and actions via group-invariant Markov Decision Processes (MDPs). However, real-world environments almost never realize fully group-invariant MDPs; dynamics, actuation limits, and reward design usually break symmetries, often only locally. Under group-invariant Bellman backups for such cases, local symmetry-breaking introduces errors that propagate across the entire state-action space, resulting in global value estimation errors. To address this, we introduce Partially group-Invariant MDP (PI-MDP), which selectively applies group-invariant or standard Bellman backups depending on where symmetry holds. This framework mitigates error propagation from locally broken symmetries while maintaining the benefits of equivariance, thereby enhancing sample efficiency and generalizability. Building on this framework, we present practical RL algorithms -- Partially Equivariant (PE)-DQN for discrete control and PE-SAC for continuous control -- that combine the benefits of equivariance with robustness to symmetry-breaking. Experiments across Grid-World, locomotion, and manipulation benchmarks demonstrate that PE-DQN and PE-SAC significantly outperform baselines, highlighting the importance of selective symmetry exploitation for robust and sample-efficient RL. Project page: https://pranaboy72.github.io/perl_page/
title Partially Equivariant Reinforcement Learning in Symmetry-Breaking Environments
topic Machine Learning
Robotics
url https://arxiv.org/abs/2512.00915