Neural Bandit Based Optimal LLM Selection for a Pipeline of Subtasks

Fuente: arXiv
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Autori principali: Atalar, Baran, Zhang, Eddie, Joe-Wong, Carlee
Natura: Preprint
Pubblicazione: 2025
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author Atalar, Baran
Zhang, Eddie
Joe-Wong, Carlee
author_facet Atalar, Baran
Zhang, Eddie
Joe-Wong, Carlee
contents As large language models (LLMs) become increasingly popular, there is a growing need to predict which out of a set of LLMs will yield a successful answer to a given query at low cost. This problem promises to become even more relevant as LLM agents are asked to solve an increasing variety of "agentic'' AI tasks. Such tasks are often broken into smaller subtasks, each of which can then be executed by a LLM expected to perform well on that specific subtask. For example, to extract a diagnosis from medical records, one can first select an LLM to summarize the record, select another to validate the summary, and then select a possibly different LLM to extract the diagnosis from the summarized record. Unlike existing LLM selection or routing algorithms, this setting requires selecting a sequence of LLMs, with the output of each LLM feeding into the next and potentially influencing its success. Thus, unlike single LLM selection, the quality of each subtask's output directly affects the inputs, and hence the cost and success rate, of downstream LLMs, creating complex performance dependencies that must be learned during selection. We propose a neural contextual bandit-based algorithm that trains neural networks to guide LLM selections for the different subtasks, without requiring historical LLM performance data. We prove that our proposed Sequential Bandits algorithm achieves a sublinear regret in the number of tasks, and we experimentally validate its superior performance compared to other LLM selection algorithms on two real datasets.
format Preprint
id arxiv_https___arxiv_org_abs_2508_09958
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Neural Bandit Based Optimal LLM Selection for a Pipeline of Subtasks
Atalar, Baran
Zhang, Eddie
Joe-Wong, Carlee
Computation and Language
Machine Learning
As large language models (LLMs) become increasingly popular, there is a growing need to predict which out of a set of LLMs will yield a successful answer to a given query at low cost. This problem promises to become even more relevant as LLM agents are asked to solve an increasing variety of "agentic'' AI tasks. Such tasks are often broken into smaller subtasks, each of which can then be executed by a LLM expected to perform well on that specific subtask. For example, to extract a diagnosis from medical records, one can first select an LLM to summarize the record, select another to validate the summary, and then select a possibly different LLM to extract the diagnosis from the summarized record. Unlike existing LLM selection or routing algorithms, this setting requires selecting a sequence of LLMs, with the output of each LLM feeding into the next and potentially influencing its success. Thus, unlike single LLM selection, the quality of each subtask's output directly affects the inputs, and hence the cost and success rate, of downstream LLMs, creating complex performance dependencies that must be learned during selection. We propose a neural contextual bandit-based algorithm that trains neural networks to guide LLM selections for the different subtasks, without requiring historical LLM performance data. We prove that our proposed Sequential Bandits algorithm achieves a sublinear regret in the number of tasks, and we experimentally validate its superior performance compared to other LLM selection algorithms on two real datasets.
title Neural Bandit Based Optimal LLM Selection for a Pipeline of Subtasks
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2508.09958