Finite-Time Analysis of Discounted Exponential-Utility Reinforcement Learning
- URL: http://arxiv.org/abs/2608.01917v1
- Date: Mon, 03 Aug 2026 08:50:07 GMT
- Title: Finite-Time Analysis of Discounted Exponential-Utility Reinforcement Learning
- Abstract summary: We provide the first finite-time guarantees for model-free discounted exponential-utility reinforcement learning.<n>These results provide the first finite-time guarantees for model-free discounted exponential-utility reinforcement learning.
- Score: 9.748884794669346
- License: http://creativecommons.org/licenses/by-sa/4.0/
- Abstract: Discounted exponential utility provides a principled criterion for risk-sensitive sequential decision-making, but its nonlinear structure complicates reinforcement learning. A recent work \citep{thoppe2026reinforcement} addressed this difficulty by introducing a Bellman-compatible surrogate and two model-free fixed-point algorithms for optimizing it over stationary policies. However, their main convergence results are asymptotic. In this work, we establish finite-time rates of $\tilde{O} (1/\sqrt{n})$ for the aforementioned two algorithms under asynchronous Markovian sampling, where $n$ is the iteration index and $\tilde{O}$ hides logarithmic expressions. Importantly, we employ parameter-free choices for the stepsize parameter to derive these rate results. For the algorithmically simpler one-timescale method, the main challenge is that its update equation is not directly aligned with the contraction geometry of its underlying power-law operator. We overcome this mismatch by exploiting the boundedness, monotonicity, and homogeneity of the operator to obtain a local pseudo-contraction property for the relative-error dynamics. We then use a Moreau-envelope-based Lyapunov function and Polyak--Ruppert averaging to obtain the stated convergence rate with parameter-free stepsizes. For the two-timescale method, the main challenge is to control a tracking error on the faster timescale. These results provide the first finite-time guarantees for model-free discounted exponential-utility reinforcement learning.
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