Tree Search-Based Policy Optimization under Stochastic Execution Delay

Fuente: arXiv
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Main Authors: Valensi, David, Derman, Esther, Mannor, Shie, Dalal, Gal
Format: Preprint
Published: 2024
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author Valensi, David
Derman, Esther
Mannor, Shie
Dalal, Gal
author_facet Valensi, David
Derman, Esther
Mannor, Shie
Dalal, Gal
contents The standard formulation of Markov decision processes (MDPs) assumes that the agent's decisions are executed immediately. However, in numerous realistic applications such as robotics or healthcare, actions are performed with a delay whose value can even be stochastic. In this work, we introduce stochastic delayed execution MDPs, a new formalism addressing random delays without resorting to state augmentation. We show that given observed delay values, it is sufficient to perform a policy search in the class of Markov policies in order to reach optimal performance, thus extending the deterministic fixed delay case. Armed with this insight, we devise DEZ, a model-based algorithm that optimizes over the class of Markov policies. DEZ leverages Monte-Carlo tree search similar to its non-delayed variant EfficientZero to accurately infer future states from the action queue. Thus, it handles delayed execution while preserving the sample efficiency of EfficientZero. Through a series of experiments on the Atari suite, we demonstrate that although the previous baseline outperforms the naive method in scenarios with constant delay, it underperforms in the face of stochastic delays. In contrast, our approach significantly outperforms the baselines, for both constant and stochastic delays. The code is available at http://github.com/davidva1/Delayed-EZ .
format Preprint
id arxiv_https___arxiv_org_abs_2404_05440
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Tree Search-Based Policy Optimization under Stochastic Execution Delay
Valensi, David
Derman, Esther
Mannor, Shie
Dalal, Gal
Artificial Intelligence
Machine Learning
The standard formulation of Markov decision processes (MDPs) assumes that the agent's decisions are executed immediately. However, in numerous realistic applications such as robotics or healthcare, actions are performed with a delay whose value can even be stochastic. In this work, we introduce stochastic delayed execution MDPs, a new formalism addressing random delays without resorting to state augmentation. We show that given observed delay values, it is sufficient to perform a policy search in the class of Markov policies in order to reach optimal performance, thus extending the deterministic fixed delay case. Armed with this insight, we devise DEZ, a model-based algorithm that optimizes over the class of Markov policies. DEZ leverages Monte-Carlo tree search similar to its non-delayed variant EfficientZero to accurately infer future states from the action queue. Thus, it handles delayed execution while preserving the sample efficiency of EfficientZero. Through a series of experiments on the Atari suite, we demonstrate that although the previous baseline outperforms the naive method in scenarios with constant delay, it underperforms in the face of stochastic delays. In contrast, our approach significantly outperforms the baselines, for both constant and stochastic delays. The code is available at http://github.com/davidva1/Delayed-EZ .
title Tree Search-Based Policy Optimization under Stochastic Execution Delay
topic Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2404.05440