Bridging Domains through Subspace-Aware Model Merging

Fuente: arXiv
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Autores principales: Chaves, Levy, Zhou, Chao, Burkholz, Rebekka, Valle, Eduardo, Avila, Sandra
Formato: Preprint
Publicado: 2026
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author Chaves, Levy
Zhou, Chao
Burkholz, Rebekka
Valle, Eduardo
Avila, Sandra
author_facet Chaves, Levy
Zhou, Chao
Burkholz, Rebekka
Valle, Eduardo
Avila, Sandra
contents Model merging integrates multiple task-specific models into a single consolidated one. Recent research has made progress in improving merging performance for in-distribution or multi-task scenarios, but domain generalization in model merging remains underexplored. We investigate how merging models fine-tuned on distinct domains affects generalization to unseen domains. Through an analysis of parameter competition in the task matrix using singular value decomposition, we show that merging models trained under different distribution shifts induces stronger conflicts between their subspaces compared to traditional multi-task settings. To mitigate this issue, we propose SCORE (Subspace COnflict-Resolving mErging), a method designed to alleviate such singular subspace conflicts. SCORE finds a shared orthogonal basis by computing the principal components of the concatenated leading singular vectors of all models. It then projects each task matrix into the shared basis, pruning off-diagonal components to remove conflicting singular directions. SCORE consistently outperforms, on average, existing model merging approaches in domain generalization settings across a variety of architectures and model scales, demonstrating its effectiveness and scalability.
format Preprint
id arxiv_https___arxiv_org_abs_2603_05768
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Bridging Domains through Subspace-Aware Model Merging
Chaves, Levy
Zhou, Chao
Burkholz, Rebekka
Valle, Eduardo
Avila, Sandra
Machine Learning
Artificial Intelligence
Computer Vision and Pattern Recognition
Model merging integrates multiple task-specific models into a single consolidated one. Recent research has made progress in improving merging performance for in-distribution or multi-task scenarios, but domain generalization in model merging remains underexplored. We investigate how merging models fine-tuned on distinct domains affects generalization to unseen domains. Through an analysis of parameter competition in the task matrix using singular value decomposition, we show that merging models trained under different distribution shifts induces stronger conflicts between their subspaces compared to traditional multi-task settings. To mitigate this issue, we propose SCORE (Subspace COnflict-Resolving mErging), a method designed to alleviate such singular subspace conflicts. SCORE finds a shared orthogonal basis by computing the principal components of the concatenated leading singular vectors of all models. It then projects each task matrix into the shared basis, pruning off-diagonal components to remove conflicting singular directions. SCORE consistently outperforms, on average, existing model merging approaches in domain generalization settings across a variety of architectures and model scales, demonstrating its effectiveness and scalability.
title Bridging Domains through Subspace-Aware Model Merging
topic Machine Learning
Artificial Intelligence
Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2603.05768