Follow-the-Perturbed-Leader for Decoupled Bandits: Best-of-Both-Worlds and Practicality

Fuente: arXiv
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Main Authors: Kim, Chaiwon, Lee, Jongyeong, Oh, Min-hwan
Format: Preprint
Published: 2025
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author Kim, Chaiwon
Lee, Jongyeong
Oh, Min-hwan
author_facet Kim, Chaiwon
Lee, Jongyeong
Oh, Min-hwan
contents We study the decoupled multi-armed bandit problem, where the learner separately selects one arm for exploration and one, possibly different, arm for exploitation at each round. In this setting, the loss of the explored arm is observed but not incurred, whereas the loss of the exploited arm is incurred without being observed. We propose an efficient Follow-the-Perturbed-Leader (FTPL) policy that achieves Best-of-Both-Worlds (BOBW) guarantee with constant regret in the stochastic regime and optimal $O(\sqrt{KT})$ regret in the adversarial regime. A key feature of our method is that it completely avoids both the convex optimization required by prior BOBW policies and the resampling procedures typically used in FTPL bandit policies. This allows FTPL to fully realize its computational efficiency advantages, leading to substantial reductions in computational cost. We empirically confirm that our policy not only improves the runtime but also demonstrates superior regret performance in both regimes.
format Preprint
id arxiv_https___arxiv_org_abs_2510_12152
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Follow-the-Perturbed-Leader for Decoupled Bandits: Best-of-Both-Worlds and Practicality
Kim, Chaiwon
Lee, Jongyeong
Oh, Min-hwan
Machine Learning
We study the decoupled multi-armed bandit problem, where the learner separately selects one arm for exploration and one, possibly different, arm for exploitation at each round. In this setting, the loss of the explored arm is observed but not incurred, whereas the loss of the exploited arm is incurred without being observed. We propose an efficient Follow-the-Perturbed-Leader (FTPL) policy that achieves Best-of-Both-Worlds (BOBW) guarantee with constant regret in the stochastic regime and optimal $O(\sqrt{KT})$ regret in the adversarial regime. A key feature of our method is that it completely avoids both the convex optimization required by prior BOBW policies and the resampling procedures typically used in FTPL bandit policies. This allows FTPL to fully realize its computational efficiency advantages, leading to substantial reductions in computational cost. We empirically confirm that our policy not only improves the runtime but also demonstrates superior regret performance in both regimes.
title Follow-the-Perturbed-Leader for Decoupled Bandits: Best-of-Both-Worlds and Practicality
topic Machine Learning
url https://arxiv.org/abs/2510.12152