In-Context Learning for Pure Exploration

Fuente: arXiv
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Main Authors: Russo, Alessio, Welch, Ryan, Pacchiano, Aldo
Format: Preprint
Published: 2025
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author Russo, Alessio
Welch, Ryan
Pacchiano, Aldo
author_facet Russo, Alessio
Welch, Ryan
Pacchiano, Aldo
contents We study the problem active sequential hypothesis testing, also known as pure exploration: given a new task, the learner adaptively collects data from the environment to efficiently determine an underlying correct hypothesis. A classical instance of this problem is the task of identifying the best arm in a multi-armed bandit problem (a.k.a. BAI, Best-Arm Identification), where actions index hypotheses. Another important case is generalized search, a problem of determining the correct label through a sequence of strategically selected queries that indirectly reveal information about the label. In this work, we introduce In-Context Pure Explorer (ICPE), which meta-trains Transformers to map observation histories to query actions and a predicted hypothesis, yielding a model that transfers in-context. At inference time, ICPE actively gathers evidence on new tasks and infers the true hypothesis without parameter updates. Across deterministic, stochastic, and structured benchmarks, including BAI and generalized search, ICPE is competitive with adaptive baselines while requiring no explicit modeling of information structure. Our results support Transformers as practical architectures for general sequential testing.
format Preprint
id arxiv_https___arxiv_org_abs_2506_01876
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle In-Context Learning for Pure Exploration
Russo, Alessio
Welch, Ryan
Pacchiano, Aldo
Machine Learning
Artificial Intelligence
We study the problem active sequential hypothesis testing, also known as pure exploration: given a new task, the learner adaptively collects data from the environment to efficiently determine an underlying correct hypothesis. A classical instance of this problem is the task of identifying the best arm in a multi-armed bandit problem (a.k.a. BAI, Best-Arm Identification), where actions index hypotheses. Another important case is generalized search, a problem of determining the correct label through a sequence of strategically selected queries that indirectly reveal information about the label. In this work, we introduce In-Context Pure Explorer (ICPE), which meta-trains Transformers to map observation histories to query actions and a predicted hypothesis, yielding a model that transfers in-context. At inference time, ICPE actively gathers evidence on new tasks and infers the true hypothesis without parameter updates. Across deterministic, stochastic, and structured benchmarks, including BAI and generalized search, ICPE is competitive with adaptive baselines while requiring no explicit modeling of information structure. Our results support Transformers as practical architectures for general sequential testing.
title In-Context Learning for Pure Exploration
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2506.01876