Model Merging via Data-Free Covariance Estimation

Fuente: arXiv
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Auteurs principaux: Hameed, Marawan Gamal Abdel, Tam, Derek, Notsawo, Pascal Jr Tikeng, Raffel, Colin, Rabusseau, Guillaume
Format: Preprint
Publié: 2026
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author Hameed, Marawan Gamal Abdel
Tam, Derek
Notsawo, Pascal Jr Tikeng
Raffel, Colin
Rabusseau, Guillaume
author_facet Hameed, Marawan Gamal Abdel
Tam, Derek
Notsawo, Pascal Jr Tikeng
Raffel, Colin
Rabusseau, Guillaume
contents Model merging provides a way of cheaply combining individual models to produce a model that inherits each individual's capabilities. While some merging methods can approach the performance of multitask training, they are often heuristically motivated and lack theoretical justification. A principled alternative is to pose model merging as a layer-wise optimization problem that directly minimizes interference between tasks. However, this formulation requires estimating per-layer covariance matrices from data, which may not be available when performing merging. In contrast, many of the heuristically-motivated methods do not require auxiliary data, making them practically advantageous. In this work, we revisit the interference minimization framework and show that, under certain conditions, covariance matrices can be estimated directly from difference matrices, eliminating the need for data while also reducing computational costs. We validate our approach across vision and language benchmarks on models ranging from 86M parameters to 7B parameters, outperforming previous data-free state-of-the-art merging methods
format Preprint
id arxiv_https___arxiv_org_abs_2604_01329
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Model Merging via Data-Free Covariance Estimation
Hameed, Marawan Gamal Abdel
Tam, Derek
Notsawo, Pascal Jr Tikeng
Raffel, Colin
Rabusseau, Guillaume
Machine Learning
Model merging provides a way of cheaply combining individual models to produce a model that inherits each individual's capabilities. While some merging methods can approach the performance of multitask training, they are often heuristically motivated and lack theoretical justification. A principled alternative is to pose model merging as a layer-wise optimization problem that directly minimizes interference between tasks. However, this formulation requires estimating per-layer covariance matrices from data, which may not be available when performing merging. In contrast, many of the heuristically-motivated methods do not require auxiliary data, making them practically advantageous. In this work, we revisit the interference minimization framework and show that, under certain conditions, covariance matrices can be estimated directly from difference matrices, eliminating the need for data while also reducing computational costs. We validate our approach across vision and language benchmarks on models ranging from 86M parameters to 7B parameters, outperforming previous data-free state-of-the-art merging methods
title Model Merging via Data-Free Covariance Estimation
topic Machine Learning
url https://arxiv.org/abs/2604.01329