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Main Authors: Mohammadabadi, Seyed Mahmoud Sajjadi, Ma, Xiaolong, Yang, Lei, Yan, Feng, Zhang, Junshan
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.08368
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author Mohammadabadi, Seyed Mahmoud Sajjadi
Ma, Xiaolong
Yang, Lei
Yan, Feng
Zhang, Junshan
author_facet Mohammadabadi, Seyed Mahmoud Sajjadi
Ma, Xiaolong
Yang, Lei
Yan, Feng
Zhang, Junshan
contents Parameter-efficient fine-tuning (PEFT) methods, such as LoRA, enable scalable adaptation of foundation models by injecting low-rank adapters. However, their communication and storage costs remain a major bottleneck in resource-constrained settings. We propose SOLAR (Subspace-Oriented Latent Adapter Reparameterization), a post-training compression framework that substantially reduces the communication cost (i.e., the number of parameters to transmit or store) of PEFT adapters. SOLAR expresses each PEFT update as a linear combination of basis vectors formed from the foundation model's singular vectors with controlled random perturbations. By exploiting the subspace similarity (the alignment of principal directions) between the foundation model and task-specific fine-tuned updates, SOLAR decouples the adapter size from PEFT structure and ensures compact yet expressive representations. It is model-agnostic and compatible with existing PEFT methods, including LoRA, AdaLoRA, and other adapter modules. We theoretically establish a bound on the reconstruction error. Experiments on language and vision tasks using LLaMA, GPT, and ViT models demonstrate that SOLAR preserves task performance while significantly reducing model representation sizes, offering an effective and communication-efficient solution for deployment in distributed systems and edge devices.
format Preprint
id arxiv_https___arxiv_org_abs_2604_08368
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle SOLAR: Communication-Efficient Model Adaptation via Subspace-Oriented Latent Adapter Reparametrization
Mohammadabadi, Seyed Mahmoud Sajjadi
Ma, Xiaolong
Yang, Lei
Yan, Feng
Zhang, Junshan
Machine Learning
Computation and Language
Computer Vision and Pattern Recognition
I.2.7; I.2.6
Parameter-efficient fine-tuning (PEFT) methods, such as LoRA, enable scalable adaptation of foundation models by injecting low-rank adapters. However, their communication and storage costs remain a major bottleneck in resource-constrained settings. We propose SOLAR (Subspace-Oriented Latent Adapter Reparameterization), a post-training compression framework that substantially reduces the communication cost (i.e., the number of parameters to transmit or store) of PEFT adapters. SOLAR expresses each PEFT update as a linear combination of basis vectors formed from the foundation model's singular vectors with controlled random perturbations. By exploiting the subspace similarity (the alignment of principal directions) between the foundation model and task-specific fine-tuned updates, SOLAR decouples the adapter size from PEFT structure and ensures compact yet expressive representations. It is model-agnostic and compatible with existing PEFT methods, including LoRA, AdaLoRA, and other adapter modules. We theoretically establish a bound on the reconstruction error. Experiments on language and vision tasks using LLaMA, GPT, and ViT models demonstrate that SOLAR preserves task performance while significantly reducing model representation sizes, offering an effective and communication-efficient solution for deployment in distributed systems and edge devices.
title SOLAR: Communication-Efficient Model Adaptation via Subspace-Oriented Latent Adapter Reparametrization
topic Machine Learning
Computation and Language
Computer Vision and Pattern Recognition
I.2.7; I.2.6
url https://arxiv.org/abs/2604.08368