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Provably Efficient Reinforcement Learning in Continuous-Time Episodic MDPs with Poisson Decision Epochs
Proceedings of the 42nd Conference on Uncertainty in Artificial Intelligence, PMLR 337:1823-1856, 2026.
Abstract
Many real-world reinforcement learning ({RL}) problems evolve in continuous time, where decisions occur at irregular, event-driven intervals rather than at fixed discrete steps. We study episodic continuous-time {Markov} Decision Processes ({MDPs}) in which decision epochs are governed by a homogeneous {Poisson} process and the reward and transition dynamics vary smoothly over time. We consider both a fixed number of jumps per episode and a fixed time budget with a random number of {Poisson} decision epochs. Under a Lipschitz continuity assumption in time, we exploit local smoothness through discretization and extend both UCRL \cite{auer2006logarithmic} and Q-learning \cite{jin2018q} to this setting, proving $\tilde{\mathcal{O}}(T^{2/3})$ regret bounds for both model-based and model-free algorithms. Finally, we establish matching $\tilde{\Omega}(T^{2/3})$ minimax lower bounds, showing that the rate is optimal up to logarithmic factors. These results provide the first tight regret guarantees for Lipschitz-smooth continuous-time episodic {MDPs} with {Poisson} decision epochs.