Near Optimal Non-asymptotic Sample Complexity of 1-Identification

ZITIAN LI, Wang Chi Cheung

TL;DR: Targeting on a open problem 1-identification, we design a new algorithm and prove matching upper and lower bounds.

Abstract:

Motivated by an open direction in existing literature, we study the 1-identification problem, a fundamental multi-armed bandit formulation on pure exploration. The goal is to determine whether there exists an arm whose mean reward is at least a known threshold $\mu_0$, or to output \textsf{None} if it believes such an arm does not exist. The agent needs to guarantee its output is correct with probability at least $1-\delta$.
Degenne & Koolen 2019 has established the asymptotically tight sample complexity for the 1-identification problem, but they commented that the non-asymptotic analysis remains unclear. We design a new algorithm Sequential-Exploration-Exploitation (SEE), and conduct theoretical analysis from the non-asymptotic perspective. Novel to the literature, we achieve near optimality, in the sense of matching upper and lower bounds on the pulling complexity. The gap between the upper and lower bounds is up to a polynomial logarithmic factor. The numerical result also indicates the effectiveness of our algorithm, compared to existing benchmarks.

Lay Summary: We work on 1-identification, which is an open problem discussed by multiple papers. We propose a new algorithm SEE to solve the problem and conduct non-asymptotic theoretical analysis on SEE. Both the theoretical and numeric performance suggest the excellency of this new algorithm. And our work fills in a blank area in the academic community.

Link To Code: https://github.com/lzt68/1-identification-ICML2025-Camera-Ready

Primary Area: Theory->Online Learning and Bandits

Keywords: 1-identification, Bandits, Complexity

Submission Number: 2993