Efficient Multi-objective Prompt Optimization via Pure-exploration Bandits

Fuente: arXiv
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Main Authors: Li, Donghao, Shi, Chengshuai, Ou, Weijuan, Shen, Cong, Yang, Jing
Format: Preprint
Published: 2026
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author Li, Donghao
Shi, Chengshuai
Ou, Weijuan
Shen, Cong
Yang, Jing
author_facet Li, Donghao
Shi, Chengshuai
Ou, Weijuan
Shen, Cong
Yang, Jing
contents Prompt engineering has become central to eliciting the capabilities of large language models (LLMs). At its core lies prompt selection -- efficiently identifying the most effective prompts. However, most prior investigations overlook a key challenge: the inherently multi-faceted nature of prompt performance, which cannot be captured by a single metric. To fill this gap, we study the multi-objective prompt selection problem under two practical settings: Pareto prompt set recovery and best feasible prompt identification. Casting the problem into the pure-exploration bandits framework, we adapt provably efficient algorithms from multi-objective bandits and further introduce a novel design for best feasible arm identification in structured bandits, with theoretical guarantees on the identification error in the linear case. Extensive experiments across multiple LLMs show that the bandit-based approaches yield significant improvements over baselines, establishing a principled and efficient framework for multi-objective prompt optimization.
format Preprint
id arxiv_https___arxiv_org_abs_2605_14553
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Efficient Multi-objective Prompt Optimization via Pure-exploration Bandits
Li, Donghao
Shi, Chengshuai
Ou, Weijuan
Shen, Cong
Yang, Jing
Machine Learning
Artificial Intelligence
Prompt engineering has become central to eliciting the capabilities of large language models (LLMs). At its core lies prompt selection -- efficiently identifying the most effective prompts. However, most prior investigations overlook a key challenge: the inherently multi-faceted nature of prompt performance, which cannot be captured by a single metric. To fill this gap, we study the multi-objective prompt selection problem under two practical settings: Pareto prompt set recovery and best feasible prompt identification. Casting the problem into the pure-exploration bandits framework, we adapt provably efficient algorithms from multi-objective bandits and further introduce a novel design for best feasible arm identification in structured bandits, with theoretical guarantees on the identification error in the linear case. Extensive experiments across multiple LLMs show that the bandit-based approaches yield significant improvements over baselines, establishing a principled and efficient framework for multi-objective prompt optimization.
title Efficient Multi-objective Prompt Optimization via Pure-exploration Bandits
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2605.14553