Non-Stationary Off-Policy Optimization

Joey Hong · Branislav Kveton · Manzil Zaheer · Yinlam Chow · Amr Ahmed

Keywords: [ Online Learning ] [ Learning Theory and Statistics ]

[ Abstract ]
Tue 13 Apr 2 p.m. PDT — 4 p.m. PDT


Off-policy learning is a framework for evaluating and optimizing policies without deploying them, from data collected by another policy. Real-world environments are typically non-stationary and the offline learned policies should adapt to these changes. To address this challenge, we study the novel problem of off-policy optimization in piecewise-stationary contextual bandits. Our proposed solution has two phases. In the offline learning phase, we partition logged data into categorical latent states and learn a near-optimal sub-policy for each state. In the online deployment phase, we adaptively switch between the learned sub-policies based on their performance. This approach is practical and analyzable, and we provide guarantees on both the quality of off-policy optimization and the regret during online deployment. To show the effectiveness of our approach, we compare it to state-of-the-art baselines on both synthetic and real-world datasets. Our approach outperforms methods that act only on observed context.

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