Thompson Sampling for Real-Valued Combinatorial Pure Exploration of Multi-Armed Bandit

• URL: http://arxiv.org/abs/2308.10238v3
• Date: Wed, 15 Nov 2023 11:00:20 GMT
• Title: Thompson Sampling for Real-Valued Combinatorial Pure Exploration of Multi-Armed Bandit
• Authors: Shintaro Nakamura, Masashi Sugiyama
• Abstract summary: We study the real-valued pure exploration of the multi-armed bandit (R-CPE-MAB) problem. We introduce an algorithm named the Generalized Thompson Sampling Explore (GenTS-Explore) algorithm, which is the first algorithm that can work even when the size of the action set is exponentially large in $d$.
• Score: 65.268245109828
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We study the real-valued combinatorial pure exploration of the multi-armed bandit (R-CPE-MAB) problem. In R-CPE-MAB, a player is given $d$ stochastic arms, and the reward of each arm $s\in\{1, \ldots, d\}$ follows an unknown distribution with mean $\mu_s$. In each time step, a player pulls a single arm and observes its reward. The player's goal is to identify the optimal \emph{action} $\boldsymbol{\pi}^{*} = \argmax_{\boldsymbol{\pi} \in \mathcal{A}} \boldsymbol{\mu}^{\top}\boldsymbol{\pi}$ from a finite-sized real-valued \emph{action set} $\mathcal{A}\subset \mathbb{R}^{d}$ with as few arm pulls as possible. Previous methods in the R-CPE-MAB assume that the size of the action set $\mathcal{A}$ is polynomial in $d$. We introduce an algorithm named the Generalized Thompson Sampling Explore (GenTS-Explore) algorithm, which is the first algorithm that can work even when the size of the action set is exponentially large in $d$. We also introduce a novel problem-dependent sample complexity lower bound of the R-CPE-MAB problem, and show that the GenTS-Explore algorithm achieves the optimal sample complexity up to a problem-dependent constant factor.

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