Asymptotically Optimal Information-Directed Sampling
Johannes Kirschner , Tor Lattimore , Claire Vernade , Csaba Szepesvari
Session: Bandits, RL and Control 2 (A)
Session Chair: Sattar Vakili
Poster: Poster Session 3
Abstract:
We introduce a simple and efficient algorithm for stochastic linear bandits with finitely many actions that is asymptotically optimal and (nearly) worst-case optimal in finite time. The approach is based on the frequentist information-directed sampling (IDS) framework, with a surrogate for the information gain that is informed by the optimization problem that defines the asymptotic lower bound. Our analysis sheds light on how IDS balances the trade-off between regret and information and uncovers a surprising connection between the recently proposed primal-dual methods and the IDS algorithm. We demonstrate empirically that IDS is competitive with UCB in finite-time, and can be significantly better in the asymptotic regime.