GroupDPO: Memory efficient Group-wise Direct Preference Optimization

Fuente: arXiv
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Autores principales: Leng, Jixuan, Si, Si, Yu, Hsiang-Fu, Raman, Vinod, Dhillon, Inderjit S.
Formato: Preprint
Publicado: 2026
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author Leng, Jixuan
Si, Si
Yu, Hsiang-Fu
Raman, Vinod
Dhillon, Inderjit S.
author_facet Leng, Jixuan
Si, Si
Yu, Hsiang-Fu
Raman, Vinod
Dhillon, Inderjit S.
contents Preference optimization is widely used to align Large Language Models (LLMs) with preference feedback. However, most existing methods train on a single positive-negative pair per prompt, discarding additional supervision available in preference datasets that typically contain multiple candidate responses. Motivated by this limitation, recent work explores group-wise preference optimization, which jointly contrasts multiple responses for the same prompt, but its empirical behavior and scalability remain underexplored due to the memory overhead of group-coupled objectives. In this work, we introduce a memory-efficient group-wise preference optimization algorithm that preserves gradients while decoupling samples during backpropagation, substantially reducing peak memory usage, which enables scalable training with larger group sizes. Across both offline and online alignment settings, we show that leveraging multiple responses consistently outperforms single-pair training. Furthermore, incorporating a negative log-likelihood (NLL) term on positive responses is critical for both performance gains and training stability.
format Preprint
id arxiv_https___arxiv_org_abs_2604_15602
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle GroupDPO: Memory efficient Group-wise Direct Preference Optimization
Leng, Jixuan
Si, Si
Yu, Hsiang-Fu
Raman, Vinod
Dhillon, Inderjit S.
Computation and Language
Preference optimization is widely used to align Large Language Models (LLMs) with preference feedback. However, most existing methods train on a single positive-negative pair per prompt, discarding additional supervision available in preference datasets that typically contain multiple candidate responses. Motivated by this limitation, recent work explores group-wise preference optimization, which jointly contrasts multiple responses for the same prompt, but its empirical behavior and scalability remain underexplored due to the memory overhead of group-coupled objectives. In this work, we introduce a memory-efficient group-wise preference optimization algorithm that preserves gradients while decoupling samples during backpropagation, substantially reducing peak memory usage, which enables scalable training with larger group sizes. Across both offline and online alignment settings, we show that leveraging multiple responses consistently outperforms single-pair training. Furthermore, incorporating a negative log-likelihood (NLL) term on positive responses is critical for both performance gains and training stability.
title GroupDPO: Memory efficient Group-wise Direct Preference Optimization
topic Computation and Language
url https://arxiv.org/abs/2604.15602