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arXiv · 2601.20714

Adapting the Behavior of Reinforcement Learning Agents to Changing Action Spaces and Reward Functions

Raul de la Rosa·Ivana Dusparic·Nicolas Cardozo
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Abstract

Reinforcement Learning (RL) agents often struggle in real-world applications where environmental conditions are non-stationary, particularly when reward functions shift or the available action space expands. This paper introduces MORPHIN, a self-adaptive Q-learning framework that enables on-the-fly adaptation without full retraining. By integrating concept drift detection with dynamic adjustments to learning and exploration hyperparameters, MORPHIN adapts agents to changes in both the reward function and on-the-fly expansions of the agent's action space, while preserving prior policy knowledge to prevent catastrophic forgetting. We validate our approach using a Gridworld benchmark and a traffic signal control simulation. The results demonstrate that MORPHIN achieves superior convergence speed and continuous adaptation compared to a standard Q-learning baseline, improving learning efficiency by up to 1.7x.

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Raul de la Rosa, Ivana Dusparic, Nicolas Cardozo. 2026-01-28. Adapting the Behavior of Reinforcement Learning Agents to Changing Action Spaces and Reward Functions. https://doi.org/10.1109/acsos-c66519.2025.00045

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