Geometry of Neural Reinforcement Learning in Continuous State and Action Spaces

Fuente: arXiv
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Main Authors: Tiwari, Saket, Gottesman, Omer, Konidaris, George
Format: Preprint
Published: 2025
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author Tiwari, Saket
Gottesman, Omer
Konidaris, George
author_facet Tiwari, Saket
Gottesman, Omer
Konidaris, George
contents Advances in reinforcement learning (RL) have led to its successful application in complex tasks with continuous state and action spaces. Despite these advances in practice, most theoretical work pertains to finite state and action spaces. We propose building a theoretical understanding of continuous state and action spaces by employing a geometric lens to understand the locally attained set of states. The set of all parametrised policies learnt through a semi-gradient based approach induces a set of attainable states in RL. We show that the training dynamics of a two-layer neural policy induce a low dimensional manifold of attainable states embedded in the high-dimensional nominal state space trained using an actor-critic algorithm. We prove that, under certain conditions, the dimensionality of this manifold is of the order of the dimensionality of the action space. This is the first result of its kind, linking the geometry of the state space to the dimensionality of the action space. We empirically corroborate this upper bound for four MuJoCo environments and also demonstrate the results in a toy environment with varying dimensionality. We also show the applicability of this theoretical result by introducing a local manifold learning layer to the policy and value function networks to improve the performance in control environments with very high degrees of freedom by changing one layer of the neural network to learn sparse representations.
format Preprint
id arxiv_https___arxiv_org_abs_2507_20853
institution arXiv
publishDate 2025
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spellingShingle Geometry of Neural Reinforcement Learning in Continuous State and Action Spaces
Tiwari, Saket
Gottesman, Omer
Konidaris, George
Machine Learning
Artificial Intelligence
Advances in reinforcement learning (RL) have led to its successful application in complex tasks with continuous state and action spaces. Despite these advances in practice, most theoretical work pertains to finite state and action spaces. We propose building a theoretical understanding of continuous state and action spaces by employing a geometric lens to understand the locally attained set of states. The set of all parametrised policies learnt through a semi-gradient based approach induces a set of attainable states in RL. We show that the training dynamics of a two-layer neural policy induce a low dimensional manifold of attainable states embedded in the high-dimensional nominal state space trained using an actor-critic algorithm. We prove that, under certain conditions, the dimensionality of this manifold is of the order of the dimensionality of the action space. This is the first result of its kind, linking the geometry of the state space to the dimensionality of the action space. We empirically corroborate this upper bound for four MuJoCo environments and also demonstrate the results in a toy environment with varying dimensionality. We also show the applicability of this theoretical result by introducing a local manifold learning layer to the policy and value function networks to improve the performance in control environments with very high degrees of freedom by changing one layer of the neural network to learn sparse representations.
title Geometry of Neural Reinforcement Learning in Continuous State and Action Spaces
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2507.20853