Teaching Precommitted Agents: Model-Free Policy Evaluation and Control in Quasi-Hyperbolic Discounted MDPs

Abstract: Time-inconsistent preferences, where agents favor smaller-sooner over larger-later rewards, are a key feature of human and animal decision-making. Quasi-Hyperbolic (QH) discounting provides a simple yet powerful model for this behavior, but its integration into the reinforcement learning (RL) framework has been limited. This paper addresses key theoretical and algorithmic gaps for precommitted agents with QH preferences. We make two primary contributions: (i) we formally characterize the structure of the optimal policy, proving for the first time that it reduces to a simple one-step non-stationary form; and (ii) we design the first practical, model-free algorithms for both policy evaluation and Q-learning in this setting, both with provable convergence guarantees. Our results provide foundational insights for incorporating QH preferences in RL.