Truthful Reverse Auctions for Adaptive Selection via Contextual Multi-Armed Bandits

Fuente: arXiv
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Hauptverfasser: Patra, Pronoy, Damle, Sankarshan, Padala, Manisha, Gujar, Sujit
Format: Preprint
Veröffentlicht: 2026
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author Patra, Pronoy
Damle, Sankarshan
Padala, Manisha
Gujar, Sujit
author_facet Patra, Pronoy
Damle, Sankarshan
Padala, Manisha
Gujar, Sujit
contents We study the problem of selecting large language models (LLMs) for user queries in settings where multiple LLM providers submit the cost of solving a query. From the users' perspective, choosing an optimal model is a sequential, query-dependent decision problem: high-capacity models offer more reliable outputs but are costlier, while lightweight models are faster and cheaper. We formalize this interaction as a reverse auction design problem with contextual online learning, where the user adaptively discovers which model performs best while eliciting costs from competing LLM providers. Existing multi-armed bandit (MAB) mechanisms focus on forward auctions and social welfare, leaving open the challenges of reverse auctions, provider-optimal outcomes, and contextual adaptation. We address these gaps by designing a resampling-based procedure that generalizes truthful forward MAB mechanisms to reverse auctions and prove that any monotone allocation rule with this procedure is truthful. Using this, we propose a contextual MAB algorithm that learns query-dependent model quality with sublinear regret. Our framework unifies mechanism design and adaptive learning, enabling efficient, truthful, and query-aware LLM selection.
format Preprint
id arxiv_https___arxiv_org_abs_2602_14476
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Truthful Reverse Auctions for Adaptive Selection via Contextual Multi-Armed Bandits
Patra, Pronoy
Damle, Sankarshan
Padala, Manisha
Gujar, Sujit
Computer Science and Game Theory
We study the problem of selecting large language models (LLMs) for user queries in settings where multiple LLM providers submit the cost of solving a query. From the users' perspective, choosing an optimal model is a sequential, query-dependent decision problem: high-capacity models offer more reliable outputs but are costlier, while lightweight models are faster and cheaper. We formalize this interaction as a reverse auction design problem with contextual online learning, where the user adaptively discovers which model performs best while eliciting costs from competing LLM providers. Existing multi-armed bandit (MAB) mechanisms focus on forward auctions and social welfare, leaving open the challenges of reverse auctions, provider-optimal outcomes, and contextual adaptation. We address these gaps by designing a resampling-based procedure that generalizes truthful forward MAB mechanisms to reverse auctions and prove that any monotone allocation rule with this procedure is truthful. Using this, we propose a contextual MAB algorithm that learns query-dependent model quality with sublinear regret. Our framework unifies mechanism design and adaptive learning, enabling efficient, truthful, and query-aware LLM selection.
title Truthful Reverse Auctions for Adaptive Selection via Contextual Multi-Armed Bandits
topic Computer Science and Game Theory
url https://arxiv.org/abs/2602.14476