Preference Distillation via Value based Reinforcement Learning

Fuente: arXiv
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Main Authors: Kwon, Minchan, Ko, Junwon, Kim, Kangil, Kim, Junmo
Format: Preprint
Published: 2025
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author Kwon, Minchan
Ko, Junwon
Kim, Kangil
Kim, Junmo
author_facet Kwon, Minchan
Ko, Junwon
Kim, Kangil
Kim, Junmo
contents Direct Preference Optimization (DPO) is a powerful paradigm to align language models with human preferences using pairwise comparisons. However, its binary win-or-loss supervision often proves insufficient for training small models with limited capacity. Prior works attempt to distill information from large teacher models using behavior cloning or KL divergence. These methods often focus on mimicking current behavior and overlook distilling reward modeling. To address this issue, we propose \textit{Teacher Value-based Knowledge Distillation} (TVKD), which introduces an auxiliary reward from the value function of the teacher model to provide a soft guide. This auxiliary reward is formulated to satisfy potential-based reward shaping, ensuring that the global reward structure and optimal policy of DPO are preserved. TVKD can be integrated into the standard DPO training framework and does not require additional rollouts. Our experimental results show that TVKD consistently improves performance across various benchmarks and model sizes.
format Preprint
id arxiv_https___arxiv_org_abs_2509_16965
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Preference Distillation via Value based Reinforcement Learning
Kwon, Minchan
Ko, Junwon
Kim, Kangil
Kim, Junmo
Computation and Language
Direct Preference Optimization (DPO) is a powerful paradigm to align language models with human preferences using pairwise comparisons. However, its binary win-or-loss supervision often proves insufficient for training small models with limited capacity. Prior works attempt to distill information from large teacher models using behavior cloning or KL divergence. These methods often focus on mimicking current behavior and overlook distilling reward modeling. To address this issue, we propose \textit{Teacher Value-based Knowledge Distillation} (TVKD), which introduces an auxiliary reward from the value function of the teacher model to provide a soft guide. This auxiliary reward is formulated to satisfy potential-based reward shaping, ensuring that the global reward structure and optimal policy of DPO are preserved. TVKD can be integrated into the standard DPO training framework and does not require additional rollouts. Our experimental results show that TVKD consistently improves performance across various benchmarks and model sizes.
title Preference Distillation via Value based Reinforcement Learning
topic Computation and Language
url https://arxiv.org/abs/2509.16965