2022/06/23 by Hu, Pihe, Chen, Yu, Huang, Longbo · 1 citation
#FOS: Computer and information sciences #Machine Learning (cs.LG)
paper · doi:10.48550/arxiv.2206.11489
We study reinforcement learning with linear function approximation where the transition probability and reward functions are linear with respect to a feature mapping \boldsymbolϕ(s,a). Specifically, we consider the episodic inhomogeneous linear Markov Decision Process (MDP), and propose a novel computation-efficient algorithm, LSVI-UCB+, which achieves an \widetildeO(Hd√(T)) regret bound where H is the episode length, d is the feature dimension, and T is the number of steps. LSVI-UCB+ builds on weighted ridge regression and upper confidence value iteration with a Bernstein-type exploration bonus. Our statistical results are obtained with novel analytical tools, including a new Bernstein self-normalized bound with conservatism on elliptical potentials, and refined analysis of the correction term. This is a minimax optimal algorithm for linear MDPs up to logarithmic factors, which closes the √(Hd) gap between the upper bound of \widetildeO(√(H3d3T)) in (Jin et al., 2020) and lower bound of Ω(Hd√(T)) for linear MDPs.