Dynamic Model Merging Made Slim

Fuente: arXiv
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Main Authors: Du, Guodong, Lin, Wanyu
Format: Preprint
Published: 2026
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author Du, Guodong
Lin, Wanyu
author_facet Du, Guodong
Lin, Wanyu
contents Model merging enables the reuse of fine-tuned models without joint training or access to original data. Dynamic merging further improves flexibility by selectively activating task-relevant parameters and efficiently composing experts across multiple tasks. However, existing dynamic methods either maintain a full shared model with tiny experts or allocate excessive capacity to experts, leading to suboptimal accuracy--efficiency trade-offs. To address this, we propose DiDi-Merging, a slim dynamic merging framework that leverages differentiable rank allocation to balance shared and expert parameters. By formulating parameter budgeting as differentiable rank optimization in low-rank modules and introducing a data-free refinement step to recover task fidelity, DiDi-Merging matches prior dynamic baselines at only 1.24x the parameters of a single fine-tuned model and surpasses them at 1.4x, substantially more compact than methods requiring > 2x storage. DiDi-Merging applies across vision, language, and multimodal tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2605_18904
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Dynamic Model Merging Made Slim
Du, Guodong
Lin, Wanyu
Machine Learning
Artificial Intelligence
Computation and Language
Model merging enables the reuse of fine-tuned models without joint training or access to original data. Dynamic merging further improves flexibility by selectively activating task-relevant parameters and efficiently composing experts across multiple tasks. However, existing dynamic methods either maintain a full shared model with tiny experts or allocate excessive capacity to experts, leading to suboptimal accuracy--efficiency trade-offs. To address this, we propose DiDi-Merging, a slim dynamic merging framework that leverages differentiable rank allocation to balance shared and expert parameters. By formulating parameter budgeting as differentiable rank optimization in low-rank modules and introducing a data-free refinement step to recover task fidelity, DiDi-Merging matches prior dynamic baselines at only 1.24x the parameters of a single fine-tuned model and surpasses them at 1.4x, substantially more compact than methods requiring > 2x storage. DiDi-Merging applies across vision, language, and multimodal tasks.
title Dynamic Model Merging Made Slim
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2605.18904