Bayesian Exploration Networks
This addresses a foundational problem in reinforcement learning for researchers and practitioners by providing a principled model-free approach to Bayes-optimal decision-making, representing a significant advance rather than an incremental improvement.
The paper tackles the lack of theoretical understanding in model-free Bayesian reinforcement learning by introducing a novel formulation and analysis showing that model-free approaches can achieve Bayes-optimal policies, with empirical results demonstrating success in tasks where existing methods fail.
Bayesian reinforcement learning (RL) offers a principled and elegant approach for sequential decision making under uncertainty. Most notably, Bayesian agents do not face an exploration/exploitation dilemma, a major pathology of frequentist methods. However theoretical understanding of model-free approaches is lacking. In this paper, we introduce a novel Bayesian model-free formulation and the first analysis showing that model-free approaches can yield Bayes-optimal policies. We show all existing model-free approaches make approximations that yield policies that can be arbitrarily Bayes-suboptimal. As a first step towards model-free Bayes optimality, we introduce the Bayesian exploration network (BEN) which uses normalising flows to model both the aleatoric uncertainty (via density estimation) and epistemic uncertainty (via variational inference) in the Bellman operator. In the limit of complete optimisation, BEN learns true Bayes-optimal policies, but like in variational expectation-maximisation, partial optimisation renders our approach tractable. Empirical results demonstrate that BEN can learn true Bayes-optimal policies in tasks where existing model-free approaches fail.