Transformers in the Dark: Navigating Unknown Search Spaces via Bandit Feedback

Fuente: arXiv
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Hauptverfasser: Kim, Jungtaek, Zeng, Thomas, Lin, Ziqian, Lee, Minjae, Lee, Chungpa, Sohn, Jy-yong, Koo, Hyung Il, Lee, Kangwook
Format: Preprint
Veröffentlicht: 2026
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author Kim, Jungtaek
Zeng, Thomas
Lin, Ziqian
Lee, Minjae
Lee, Chungpa
Sohn, Jy-yong
Koo, Hyung Il
Lee, Kangwook
author_facet Kim, Jungtaek
Zeng, Thomas
Lin, Ziqian
Lee, Minjae
Lee, Chungpa
Sohn, Jy-yong
Koo, Hyung Il
Lee, Kangwook
contents Effective problem solving with Large Language Models (LLMs) can be enhanced when they are paired with external search algorithms. By viewing the space of diverse ideas and their follow-up possibilities as a tree structure, the search algorithm can navigate such a search space and guide the LLM toward better solutions more efficiently. While the search algorithm enables an effective balance between exploitation and exploration of a tree-structured space, the need for an external component can complicate the overall problem-solving process. We therefore pose the following question: Can LLMs or their underlying Transformer architectures approximate a search algorithm? To answer this question, we first introduce a simplified framework in which tree extensions and feedback signals are externally specified, allowing for controlled evaluation of search capabilities. We call this setting unknown tree search with bandit feedback. Within this setting, we show that Transformers are theoretically expressive enough to implement distinct search strategies and can be trained from scratch to approximate those strategies. Our Transformer models exhibit the possibility of generalizing to unseen conditions such as longer horizons or deeper trees. Furthermore, we demonstrate that continued task-focused training unlocks the complete capabilities of a pretrained LLM, by fine-tuning the LLM on search trajectories.
format Preprint
id arxiv_https___arxiv_org_abs_2603_24780
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Transformers in the Dark: Navigating Unknown Search Spaces via Bandit Feedback
Kim, Jungtaek
Zeng, Thomas
Lin, Ziqian
Lee, Minjae
Lee, Chungpa
Sohn, Jy-yong
Koo, Hyung Il
Lee, Kangwook
Machine Learning
Effective problem solving with Large Language Models (LLMs) can be enhanced when they are paired with external search algorithms. By viewing the space of diverse ideas and their follow-up possibilities as a tree structure, the search algorithm can navigate such a search space and guide the LLM toward better solutions more efficiently. While the search algorithm enables an effective balance between exploitation and exploration of a tree-structured space, the need for an external component can complicate the overall problem-solving process. We therefore pose the following question: Can LLMs or their underlying Transformer architectures approximate a search algorithm? To answer this question, we first introduce a simplified framework in which tree extensions and feedback signals are externally specified, allowing for controlled evaluation of search capabilities. We call this setting unknown tree search with bandit feedback. Within this setting, we show that Transformers are theoretically expressive enough to implement distinct search strategies and can be trained from scratch to approximate those strategies. Our Transformer models exhibit the possibility of generalizing to unseen conditions such as longer horizons or deeper trees. Furthermore, we demonstrate that continued task-focused training unlocks the complete capabilities of a pretrained LLM, by fine-tuning the LLM on search trajectories.
title Transformers in the Dark: Navigating Unknown Search Spaces via Bandit Feedback
topic Machine Learning
url https://arxiv.org/abs/2603.24780