Logits are All We Need to Adapt Closed Models

Fuente: arXiv
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Main Authors: Hiranandani, Gaurush, Wu, Haolun, Mukherjee, Subhojyoti, Koyejo, Sanmi
Format: Preprint
Published: 2025
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author Hiranandani, Gaurush
Wu, Haolun
Mukherjee, Subhojyoti
Koyejo, Sanmi
author_facet Hiranandani, Gaurush
Wu, Haolun
Mukherjee, Subhojyoti
Koyejo, Sanmi
contents Many commercial Large Language Models (LLMs) are often closed-source, limiting developers to prompt tuning for aligning content generation with specific applications. While these models currently do not provide access to token logits, we argue that if such access were available, it would enable more powerful adaptation techniques beyond prompt engineering. In this paper, we propose a token-level probability reweighting framework that, given access to logits and a small amount of task-specific data, can effectively steer black-box LLMs toward application-specific content generation. Our approach views next-token prediction through the lens of supervised classification. We show that aligning black-box LLMs with task-specific data can be formulated as a label noise correction problem, leading to Plugin model -- an autoregressive probability reweighting model that operates solely on logits. We provide theoretical justification for why reweighting logits alone is sufficient for task adaptation. Extensive experiments with multiple datasets, LLMs, and reweighting models demonstrate the effectiveness of our method, advocating for broader access to token logits in closed-source models.
format Preprint
id arxiv_https___arxiv_org_abs_2502_06806
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Logits are All We Need to Adapt Closed Models
Hiranandani, Gaurush
Wu, Haolun
Mukherjee, Subhojyoti
Koyejo, Sanmi
Machine Learning
Artificial Intelligence
Computation and Language
Many commercial Large Language Models (LLMs) are often closed-source, limiting developers to prompt tuning for aligning content generation with specific applications. While these models currently do not provide access to token logits, we argue that if such access were available, it would enable more powerful adaptation techniques beyond prompt engineering. In this paper, we propose a token-level probability reweighting framework that, given access to logits and a small amount of task-specific data, can effectively steer black-box LLMs toward application-specific content generation. Our approach views next-token prediction through the lens of supervised classification. We show that aligning black-box LLMs with task-specific data can be formulated as a label noise correction problem, leading to Plugin model -- an autoregressive probability reweighting model that operates solely on logits. We provide theoretical justification for why reweighting logits alone is sufficient for task adaptation. Extensive experiments with multiple datasets, LLMs, and reweighting models demonstrate the effectiveness of our method, advocating for broader access to token logits in closed-source models.
title Logits are All We Need to Adapt Closed Models
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2502.06806