POME: Post Optimization Model Edit via Muon-style Projection

Fuente: arXiv
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Main Authors: Liu, Yong, Fu, Di, Luo, Yang, Zhu, Zirui, Cheng, Minhao, Hsieh, Cho-Jui, You, Yang
Format: Preprint
Published: 2025
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author Liu, Yong
Fu, Di
Luo, Yang
Zhu, Zirui
Cheng, Minhao
Hsieh, Cho-Jui
You, Yang
author_facet Liu, Yong
Fu, Di
Luo, Yang
Zhu, Zirui
Cheng, Minhao
Hsieh, Cho-Jui
You, Yang
contents We introduce Post-Optimization Model Edit (POME), a new algorithm that enhances the performance of fine-tuned large language models using only their pretrained and fine-tuned checkpoints, without requiring extra data or further optimization. The core idea is to apply a muon-style projection to $ΔW$, the difference between the fine-tuned and pretrained weights. This projection uses truncated singular value decomposition (SVD) to equalize the influence of dominant update directions and prune small singular values, which often represent noise. As a simple post-processing step, POME is completely decoupled from the training pipeline. It requires zero modifications and imposes no overhead, making it universally compatible with any optimizer or distributed framework. POME delivers consistent gains, boosting average performance by +2.5\% on GSM8K and +1.0\% on code generation. Its broad applicability -- from 7B foundation models to 72B RLHF-instructed models -- establishes it as a practical, zero-cost enhancement for any fine-tuning pipeline. Code is available at https://github.com/NUS-HPC-AI-Lab/POME.
format Preprint
id arxiv_https___arxiv_org_abs_2510_06627
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle POME: Post Optimization Model Edit via Muon-style Projection
Liu, Yong
Fu, Di
Luo, Yang
Zhu, Zirui
Cheng, Minhao
Hsieh, Cho-Jui
You, Yang
Machine Learning
We introduce Post-Optimization Model Edit (POME), a new algorithm that enhances the performance of fine-tuned large language models using only their pretrained and fine-tuned checkpoints, without requiring extra data or further optimization. The core idea is to apply a muon-style projection to $ΔW$, the difference between the fine-tuned and pretrained weights. This projection uses truncated singular value decomposition (SVD) to equalize the influence of dominant update directions and prune small singular values, which often represent noise. As a simple post-processing step, POME is completely decoupled from the training pipeline. It requires zero modifications and imposes no overhead, making it universally compatible with any optimizer or distributed framework. POME delivers consistent gains, boosting average performance by +2.5\% on GSM8K and +1.0\% on code generation. Its broad applicability -- from 7B foundation models to 72B RLHF-instructed models -- establishes it as a practical, zero-cost enhancement for any fine-tuning pipeline. Code is available at https://github.com/NUS-HPC-AI-Lab/POME.
title POME: Post Optimization Model Edit via Muon-style Projection
topic Machine Learning
url https://arxiv.org/abs/2510.06627