Portable Reward Tuning: Towards Reusable Fine-Tuning across Different Pretrained Models

Fuente: arXiv
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Autori principali: Chijiwa, Daiki, Hasegawa, Taku, Nishida, Kyosuke, Saito, Kuniko, Takeuchi, Susumu
Natura: Preprint
Pubblicazione: 2025
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author Chijiwa, Daiki
Hasegawa, Taku
Nishida, Kyosuke
Saito, Kuniko
Takeuchi, Susumu
author_facet Chijiwa, Daiki
Hasegawa, Taku
Nishida, Kyosuke
Saito, Kuniko
Takeuchi, Susumu
contents While foundation models have been exploited for various expert tasks through fine-tuning, any foundation model will become outdated due to its old knowledge or limited capability. Thus the underlying foundation model should be eventually replaced by new ones, which leads to repeated cost of fine-tuning these new models. Existing work addresses this problem by inference-time tuning, i.e., modifying the output probabilities from the new foundation model with the outputs from the old foundation model and its fine-tuned model, which involves an additional overhead in inference by the latter two models. In this paper, we propose a new fine-tuning principle, Portable Reward Tuning (PRT), that reduces the inference overhead by its nature, based on the reformulation of fine-tuning as the reward maximization. Specifically, instead of fine-tuning parameters of the foundation models, PRT trains the reward model explicitly through the same loss function as in fine-tuning. During inference, the reward model can be used with any foundation model (with the same set of vocabularies or labels) through the formulation of reward maximization. Experimental results, covering both vision and language models, demonstrate that the PRT-trained model can achieve comparable accuracy to the existing work of inference-time tuning, with less inference cost.
format Preprint
id arxiv_https___arxiv_org_abs_2502_12776
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Portable Reward Tuning: Towards Reusable Fine-Tuning across Different Pretrained Models
Chijiwa, Daiki
Hasegawa, Taku
Nishida, Kyosuke
Saito, Kuniko
Takeuchi, Susumu
Machine Learning
Artificial Intelligence
While foundation models have been exploited for various expert tasks through fine-tuning, any foundation model will become outdated due to its old knowledge or limited capability. Thus the underlying foundation model should be eventually replaced by new ones, which leads to repeated cost of fine-tuning these new models. Existing work addresses this problem by inference-time tuning, i.e., modifying the output probabilities from the new foundation model with the outputs from the old foundation model and its fine-tuned model, which involves an additional overhead in inference by the latter two models. In this paper, we propose a new fine-tuning principle, Portable Reward Tuning (PRT), that reduces the inference overhead by its nature, based on the reformulation of fine-tuning as the reward maximization. Specifically, instead of fine-tuning parameters of the foundation models, PRT trains the reward model explicitly through the same loss function as in fine-tuning. During inference, the reward model can be used with any foundation model (with the same set of vocabularies or labels) through the formulation of reward maximization. Experimental results, covering both vision and language models, demonstrate that the PRT-trained model can achieve comparable accuracy to the existing work of inference-time tuning, with less inference cost.
title Portable Reward Tuning: Towards Reusable Fine-Tuning across Different Pretrained Models
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2502.12776