This was part of Reinforcement Learning from Offline Data and Human Feedback

Non-Asymptotic CLTs and Concentration Inequalities for Stochastic Approximation Algorithms, with Applications to Reinforcement Learning

R. Srikant, University of Illinois at Urbana-Champaign

Wednesday, April 22, 2026



Abstract: We present non-asymptotic CLT error bounds for stochastic approximation algorithms in the Wasserstein-p distance. To obtain explicit finite-sample guarantees for the last iterate, we develop a coupling argument that compares the discrete-time process to a limiting Ornstein-Uhlenbeck process. Our analysis applies to algorithms driven by general noise conditions, including martingale differences and functions of ergodic Markov chains. Complementing this result, we handle the convergence rate of the Polyak-Ruppert average through a direct analysis that applies under the same general setting. We demonstrate the utility of this approach by considering an application to TD learning, where we explicitly quantify the transition from heavy-tailed to Gaussian behavior of the iterates, thereby bridging the gap between recent finite-sample analyses and asymptotic theory. Based on joint work with Seo Taek Kong.