SymLight: Exploring Interpretable and Deployable Symbolic Policies for Traffic Signal Control

Fuente: arXiv
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Auteurs principaux: Liao, Xiao-Cheng, Mei, Yi, Zhang, Mengjie
Format: Preprint
Publié: 2025
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author Liao, Xiao-Cheng
Mei, Yi
Zhang, Mengjie
author_facet Liao, Xiao-Cheng
Mei, Yi
Zhang, Mengjie
contents Deep Reinforcement Learning have achieved significant success in automatically devising effective traffic signal control (TSC) policies. Neural policies, however, tend to be over-parameterized and non-transparent, hindering their interpretability and deployability on resource-limited edge devices. This work presents SymLight, a priority function search framework based on Monte Carlo Tree Search (MCTS) for discovering inherently interpretable and deployable symbolic priority functions to serve as the TSC policies. The priority function, in particular, accepts traffic features as input and then outputs a priority for each traffic signal phase, which subsequently directs the phase transition. For effective search, we propose a concise yet expressive priority function representation. This helps mitigate the combinatorial explosion of the action space in MCTS. Additionally, a probabilistic structural rollout strategy is introduced to leverage structural patterns from previously discovered high-quality priority functions, guiding the rollout process. Our experiments on real-world datasets demonstrate SymLight's superior performance across a range of baselines. A key advantage is SymLight's ability to produce interpretable and deployable TSC policies while maintaining excellent performance.
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publishDate 2025
record_format arxiv
spellingShingle SymLight: Exploring Interpretable and Deployable Symbolic Policies for Traffic Signal Control
Liao, Xiao-Cheng
Mei, Yi
Zhang, Mengjie
Machine Learning
Artificial Intelligence
Deep Reinforcement Learning have achieved significant success in automatically devising effective traffic signal control (TSC) policies. Neural policies, however, tend to be over-parameterized and non-transparent, hindering their interpretability and deployability on resource-limited edge devices. This work presents SymLight, a priority function search framework based on Monte Carlo Tree Search (MCTS) for discovering inherently interpretable and deployable symbolic priority functions to serve as the TSC policies. The priority function, in particular, accepts traffic features as input and then outputs a priority for each traffic signal phase, which subsequently directs the phase transition. For effective search, we propose a concise yet expressive priority function representation. This helps mitigate the combinatorial explosion of the action space in MCTS. Additionally, a probabilistic structural rollout strategy is introduced to leverage structural patterns from previously discovered high-quality priority functions, guiding the rollout process. Our experiments on real-world datasets demonstrate SymLight's superior performance across a range of baselines. A key advantage is SymLight's ability to produce interpretable and deployable TSC policies while maintaining excellent performance.
title SymLight: Exploring Interpretable and Deployable Symbolic Policies for Traffic Signal Control
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2511.05790