Provably Efficient UCB-type Algorithms For Learning Predictive State Representations

Published: 16 Jan 2024, Last Modified: 11 Mar 2024ICLR 2024 posterEveryoneRevisionsBibTeX
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Keywords: Reinforcement learning, Sequential decision-making problem, Predictive state representation, POMDP, UCB, online and offline
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TL;DR: We developed a provably efficient upper confidence bound algorithm for online and offline low rank decision-making problem, which is modeled by predictive state representation.
Abstract: The general sequential decision-making problem, which includes Markov decision processes (MDPs) and partially observable MDPs (POMDPs) as special cases, aims at maximizing a cumulative reward by making a sequence of decisions based on a history of observations and actions over time. Recent studies have shown that the sequential decision-making problem is statistically learnable if it admits a low-rank structure modeled by predictive state representations (PSRs). Despite these advancements, existing approaches typically involve oracles or steps that are computationally intractable. On the other hand, the upper confidence bound (UCB) based approaches, which have served successfully as computationally efficient methods in bandits and MDPs, have not been investigated for more general PSRs, due to the difficulty of optimistic bonus design in these more challenging settings. This paper proposes the first known UCB-type approach for PSRs, featuring a novel bonus term that upper bounds the total variation distance between the estimated and true models. We further characterize the sample complexity bounds for our designed UCB-type algorithms for both online and offline PSRs. In contrast to existing approaches for PSRs, our UCB-type algorithms enjoy computational tractability, last-iterate guaranteed near-optimal policy, and guaranteed model accuracy.
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Primary Area: reinforcement learning
Submission Number: 5853
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