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Main Authors: Li, Jin, Wu, Yue, Huang, Mengsha, Sun, Yuhao, He, Hao, Zhan, Xianyuan
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2602.01196
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author Li, Jin
Wu, Yue
Huang, Mengsha
Sun, Yuhao
He, Hao
Zhan, Xianyuan
author_facet Li, Jin
Wu, Yue
Huang, Mengsha
Sun, Yuhao
He, Hao
Zhan, Xianyuan
contents Recurrent neural policies are widely used in partially observable control and meta-RL tasks. Their abilities to maintain internal memory and adapt quickly to unseen scenarios have offered them unparalleled performance when compared to non-recurrent counterparts. However, until today, the underlying mechanisms for their superior generalization and robustness performance remain poorly understood. In this study, by analyzing the hidden state domain of recurrent policies learned over a diverse set of training methods, model architectures, and tasks, we find that stable cyclic structures consistently emerge during interaction with the environment. Such cyclic structures share a remarkable similarity with \textit{limit cycles} in dynamical system analysis, if we consider the policy and the environment as a joint hybrid dynamical system. Moreover, we uncover that the geometry of such limit cycles also has a structured correspondence with the policies' behaviors. These findings offer new perspectives to explain many nice properties of recurrent policies: the emergence of limit cycles stabilizes both the policies' internal memory and the task-relevant environmental states, while suppressing nuisance variability arising from environmental uncertainty; the geometry of limit cycles also encodes relational structures of behaviors, facilitating easier skill adaptation when facing non-stationary environments.
format Preprint
id arxiv_https___arxiv_org_abs_2602_01196
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Unraveling the Hidden Dynamical Structure in Recurrent Neural Policies
Li, Jin
Wu, Yue
Huang, Mengsha
Sun, Yuhao
He, Hao
Zhan, Xianyuan
Machine Learning
Recurrent neural policies are widely used in partially observable control and meta-RL tasks. Their abilities to maintain internal memory and adapt quickly to unseen scenarios have offered them unparalleled performance when compared to non-recurrent counterparts. However, until today, the underlying mechanisms for their superior generalization and robustness performance remain poorly understood. In this study, by analyzing the hidden state domain of recurrent policies learned over a diverse set of training methods, model architectures, and tasks, we find that stable cyclic structures consistently emerge during interaction with the environment. Such cyclic structures share a remarkable similarity with \textit{limit cycles} in dynamical system analysis, if we consider the policy and the environment as a joint hybrid dynamical system. Moreover, we uncover that the geometry of such limit cycles also has a structured correspondence with the policies' behaviors. These findings offer new perspectives to explain many nice properties of recurrent policies: the emergence of limit cycles stabilizes both the policies' internal memory and the task-relevant environmental states, while suppressing nuisance variability arising from environmental uncertainty; the geometry of limit cycles also encodes relational structures of behaviors, facilitating easier skill adaptation when facing non-stationary environments.
title Unraveling the Hidden Dynamical Structure in Recurrent Neural Policies
topic Machine Learning
url https://arxiv.org/abs/2602.01196