IPO: Your Language Model is Secretly a Preference Classifier

Fuente: arXiv
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Auteurs principaux: Garg, Shivank, Singh, Ayush, Singh, Shweta, Chopra, Paras
Format: Preprint
Publié: 2025
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author Garg, Shivank
Singh, Ayush
Singh, Shweta
Chopra, Paras
author_facet Garg, Shivank
Singh, Ayush
Singh, Shweta
Chopra, Paras
contents Reinforcement learning from human feedback (RLHF) has emerged as the primary method for aligning large language models (LLMs) with human preferences. While it enables LLMs to achieve human-level alignment, it often incurs significant computational and financial costs due to its reliance on training external reward models or human-labeled preferences. In this work, we propose Implicit Preference Optimization (IPO), an alternative approach that leverages generative LLMs as preference classifiers, thereby reducing the dependence on external human feedback or reward models to obtain preferences. We conduct a comprehensive evaluation on the preference classification ability of LLMs using RewardBench, assessing models across different sizes, architectures, and training levels to validate our hypothesis. Furthermore, we investigate the self-improvement capabilities of LLMs by generating multiple responses for a given instruction and employing the model itself as a preference classifier for Direct Preference Optimization (DPO)-based training. Our findings demonstrate that models trained through IPO achieve performance comparable to those utilizing state-of-the-art reward models for obtaining preferences.
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id arxiv_https___arxiv_org_abs_2502_16182
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle IPO: Your Language Model is Secretly a Preference Classifier
Garg, Shivank
Singh, Ayush
Singh, Shweta
Chopra, Paras
Computation and Language
Reinforcement learning from human feedback (RLHF) has emerged as the primary method for aligning large language models (LLMs) with human preferences. While it enables LLMs to achieve human-level alignment, it often incurs significant computational and financial costs due to its reliance on training external reward models or human-labeled preferences. In this work, we propose Implicit Preference Optimization (IPO), an alternative approach that leverages generative LLMs as preference classifiers, thereby reducing the dependence on external human feedback or reward models to obtain preferences. We conduct a comprehensive evaluation on the preference classification ability of LLMs using RewardBench, assessing models across different sizes, architectures, and training levels to validate our hypothesis. Furthermore, we investigate the self-improvement capabilities of LLMs by generating multiple responses for a given instruction and employing the model itself as a preference classifier for Direct Preference Optimization (DPO)-based training. Our findings demonstrate that models trained through IPO achieve performance comparable to those utilizing state-of-the-art reward models for obtaining preferences.
title IPO: Your Language Model is Secretly a Preference Classifier
topic Computation and Language
url https://arxiv.org/abs/2502.16182