Explainable Reinforcement Learning via Temporal Policy Decomposition

Fuente: arXiv
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Main Authors: Ruggeri, Franco, Russo, Alessio, Inam, Rafia, Johansson, Karl Henrik
Format: Preprint
Published: 2025
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author Ruggeri, Franco
Russo, Alessio
Inam, Rafia
Johansson, Karl Henrik
author_facet Ruggeri, Franco
Russo, Alessio
Inam, Rafia
Johansson, Karl Henrik
contents We investigate the explainability of Reinforcement Learning (RL) policies from a temporal perspective, focusing on the sequence of future outcomes associated with individual actions. In RL, value functions compress information about rewards collected across multiple trajectories and over an infinite horizon, allowing a compact form of knowledge representation. However, this compression obscures the temporal details inherent in sequential decision-making, presenting a key challenge for interpretability. We present Temporal Policy Decomposition (TPD), a novel explainability approach that explains individual RL actions in terms of their Expected Future Outcome (EFO). These explanations decompose generalized value functions into a sequence of EFOs, one for each time step up to a prediction horizon of interest, revealing insights into when specific outcomes are expected to occur. We leverage fixed-horizon temporal difference learning to devise an off-policy method for learning EFOs for both optimal and suboptimal actions, enabling contrastive explanations consisting of EFOs for different state-action pairs. Our experiments demonstrate that TPD generates accurate explanations that (i) clarify the policy's future strategy and anticipated trajectory for a given action and (ii) improve understanding of the reward composition, facilitating fine-tuning of the reward function to align with human expectations.
format Preprint
id arxiv_https___arxiv_org_abs_2501_03902
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Explainable Reinforcement Learning via Temporal Policy Decomposition
Ruggeri, Franco
Russo, Alessio
Inam, Rafia
Johansson, Karl Henrik
Machine Learning
Artificial Intelligence
We investigate the explainability of Reinforcement Learning (RL) policies from a temporal perspective, focusing on the sequence of future outcomes associated with individual actions. In RL, value functions compress information about rewards collected across multiple trajectories and over an infinite horizon, allowing a compact form of knowledge representation. However, this compression obscures the temporal details inherent in sequential decision-making, presenting a key challenge for interpretability. We present Temporal Policy Decomposition (TPD), a novel explainability approach that explains individual RL actions in terms of their Expected Future Outcome (EFO). These explanations decompose generalized value functions into a sequence of EFOs, one for each time step up to a prediction horizon of interest, revealing insights into when specific outcomes are expected to occur. We leverage fixed-horizon temporal difference learning to devise an off-policy method for learning EFOs for both optimal and suboptimal actions, enabling contrastive explanations consisting of EFOs for different state-action pairs. Our experiments demonstrate that TPD generates accurate explanations that (i) clarify the policy's future strategy and anticipated trajectory for a given action and (ii) improve understanding of the reward composition, facilitating fine-tuning of the reward function to align with human expectations.
title Explainable Reinforcement Learning via Temporal Policy Decomposition
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2501.03902