Is Bellman Equation Enough for Learning Control?

Fuente: arXiv
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Hauptverfasser: You, Haoxiang, Molu, Lekan, Abraham, Ian
Format: Preprint
Veröffentlicht: 2025
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author You, Haoxiang
Molu, Lekan
Abraham, Ian
author_facet You, Haoxiang
Molu, Lekan
Abraham, Ian
contents The Bellman equation and its continuous-time counterpart, the Hamilton-Jacobi-Bellman (HJB) equation, serve as necessary conditions for optimality in reinforcement learning and optimal control. While the value function is known to be the unique solution to the Bellman equation in tabular settings, we demonstrate that this uniqueness fails to hold in continuous state spaces. Specifically, for linear dynamical systems, we prove the Bellman equation admits at least $\binom{2n}{n}$ solutions, where $n$ is the state dimension. Crucially, only one of these solutions yields both an optimal policy and a stable closed-loop system. We then demonstrate a common failure mode in value-based methods: convergence to unstable solutions due to the exponential imbalance between admissible and inadmissible solutions. Finally, we introduce a positive-definite neural architecture that guarantees convergence to the stable solution by construction to address this issue.
format Preprint
id arxiv_https___arxiv_org_abs_2503_02171
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Is Bellman Equation Enough for Learning Control?
You, Haoxiang
Molu, Lekan
Abraham, Ian
Machine Learning
Optimization and Control
The Bellman equation and its continuous-time counterpart, the Hamilton-Jacobi-Bellman (HJB) equation, serve as necessary conditions for optimality in reinforcement learning and optimal control. While the value function is known to be the unique solution to the Bellman equation in tabular settings, we demonstrate that this uniqueness fails to hold in continuous state spaces. Specifically, for linear dynamical systems, we prove the Bellman equation admits at least $\binom{2n}{n}$ solutions, where $n$ is the state dimension. Crucially, only one of these solutions yields both an optimal policy and a stable closed-loop system. We then demonstrate a common failure mode in value-based methods: convergence to unstable solutions due to the exponential imbalance between admissible and inadmissible solutions. Finally, we introduce a positive-definite neural architecture that guarantees convergence to the stable solution by construction to address this issue.
title Is Bellman Equation Enough for Learning Control?
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2503.02171