The Adaptivity Barrier in Batched Nonparametric Bandits: Sharp Characterization of the Price of Unknown Margin

arXiv — stat.MLWednesday, November 12, 2025 at 5:00:00 AM
The study on batched nonparametric contextual bandits addresses the complexities introduced by an unknown margin parameter, which is crucial for optimizing algorithm performance. By defining the regret inflation criterion, the researchers quantify the disparity between adaptive algorithms and an oracle that possesses complete knowledge of the margin. Their findings show that optimal regret inflation grows polynomially with the horizon, leading to the creation of RoBIN, a robust algorithm designed to achieve optimal performance despite the unknown margin. This research uncovers a new adaptivity barrier, indicating that adapting to an unknown margin incurs a polynomial penalty. However, this barrier diminishes when the number of batches surpasses a certain threshold, specifically when it exceeds the order of log log T. Such insights are vital for advancing the field of contextual bandits and improving algorithmic strategies in uncertain environments.
— via World Pulse Now AI Editorial System

Was this article worth reading? Share it