• Corpus ID: 246430299

Coordinated Attacks against Contextual Bandits: Fundamental Limits and Defense Mechanisms

  title={Coordinated Attacks against Contextual Bandits: Fundamental Limits and Defense Mechanisms},
  author={Jeongyeol Kwon and Yonathan Efroni and Constantine Caramanis and Shie Mannor},
Motivated by online recommendation systems, we propose the problem of finding the optimal policy in multitask contextual bandits when a small fraction α < 1 / 2 of tasks (users) are arbitrary and adversarial. The remaining fraction of good users share the same instance of contextual bandits with S contexts and A actions (items). Naturally, whether a user is good or adversarial is not known in advance. The goal is to robustly learn the policy that maximizes rewards for good users with as few… 
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