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Main Authors: Guo, Siqi, Hong, Ilgee, Balmaseda, Vicente, Yu, Changlong, Qiu, Liang, Liu, Xin, Jiang, Haoming, Zhao, Tuo, Yang, Tianbao
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2502.18679
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author Guo, Siqi
Hong, Ilgee
Balmaseda, Vicente
Yu, Changlong
Qiu, Liang
Liu, Xin
Jiang, Haoming
Zhao, Tuo
Yang, Tianbao
author_facet Guo, Siqi
Hong, Ilgee
Balmaseda, Vicente
Yu, Changlong
Qiu, Liang
Liu, Xin
Jiang, Haoming
Zhao, Tuo
Yang, Tianbao
contents Supervised fine-tuning (SFT) has become a crucial step for aligning pretrained large language models (LLMs) using supervised datasets of input-output pairs. However, despite being supervised, SFT is inherently limited by its generative training objective. To address its limitations, the existing common strategy is to follow SFT with a separate phase of preference optimization (PO), which relies on either human-labeled preference data or a strong reward model to guide the learning process. In this paper, we address the limitations of SFT by exploring one of the most successful techniques in conventional supervised learning: discriminative learning. We introduce Discriminative Fine-Tuning (DFT), an improved variant of SFT, which mitigates the burden of collecting human-labeled preference data or training strong reward models. Unlike SFT that employs a generative approach and overlooks negative data, DFT adopts a discriminative paradigm that increases the probability of positive answers while suppressing potentially negative ones, aiming for data prediction instead of token prediction. Our contributions include: (i) a discriminative probabilistic framework for fine-tuning LLMs by explicitly modeling the discriminative likelihood of an answer among all possible outputs given an input; (ii) efficient algorithms to optimize this discriminative likelihood; and (iii) extensive experiments demonstrating DFT's effectiveness, achieving performance better than SFT and comparable to if not better than SFT$\rightarrow$PO. The code can be found at https://github.com/Optimization-AI/DFT.
format Preprint
id arxiv_https___arxiv_org_abs_2502_18679
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Discriminative Finetuning of Generative Large Language Models without Reward Models and Human Preference Data
Guo, Siqi
Hong, Ilgee
Balmaseda, Vicente
Yu, Changlong
Qiu, Liang
Liu, Xin
Jiang, Haoming
Zhao, Tuo
Yang, Tianbao
Computation and Language
Supervised fine-tuning (SFT) has become a crucial step for aligning pretrained large language models (LLMs) using supervised datasets of input-output pairs. However, despite being supervised, SFT is inherently limited by its generative training objective. To address its limitations, the existing common strategy is to follow SFT with a separate phase of preference optimization (PO), which relies on either human-labeled preference data or a strong reward model to guide the learning process. In this paper, we address the limitations of SFT by exploring one of the most successful techniques in conventional supervised learning: discriminative learning. We introduce Discriminative Fine-Tuning (DFT), an improved variant of SFT, which mitigates the burden of collecting human-labeled preference data or training strong reward models. Unlike SFT that employs a generative approach and overlooks negative data, DFT adopts a discriminative paradigm that increases the probability of positive answers while suppressing potentially negative ones, aiming for data prediction instead of token prediction. Our contributions include: (i) a discriminative probabilistic framework for fine-tuning LLMs by explicitly modeling the discriminative likelihood of an answer among all possible outputs given an input; (ii) efficient algorithms to optimize this discriminative likelihood; and (iii) extensive experiments demonstrating DFT's effectiveness, achieving performance better than SFT and comparable to if not better than SFT$\rightarrow$PO. The code can be found at https://github.com/Optimization-AI/DFT.
title Discriminative Finetuning of Generative Large Language Models without Reward Models and Human Preference Data
topic Computation and Language
url https://arxiv.org/abs/2502.18679