@inproceedings{xiao-etal-2026-directions,
title = "Not All Directions Matter: Towards Structured and Task-Aware Low-Rank Model Adaptation",
author = "Xiao, Xi and
Ma, Chenrui and
Zhang, Yunbei and
Liu, Chen and
Wang, Zhuxuanzi and
Li, Yanshu and
Zhao, Lin and
Hu, Guosheng and
Wang, Tianyang and
Xu, Hao",
editor = "Liakata, Maria and
Moreira, Viviane P. and
Zhang, Jiajun and
Jurgens, David",
booktitle = "Proceedings of the 64th Annual Meeting of the {A}ssociation for {C}omputational {L}inguistics (Volume 1: Long Papers)",
month = jul,
year = "2026",
address = "San Diego, California, United States",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.acl-long.97/",
pages = "2132--2154",
ISBN = "979-8-89176-390-6",
abstract = "Low-Rank Adaptation (LoRA) has become a cornerstone of parameter-efficient fine-tuning (PEFT). Yet, its efficacy is hampered by two fundamental limitations: $\textit{semantic drift}$, arising from treating all update directions with equal importance, and $\textit{structural incoherence}$, due to adapting layers independently, resulting in uncoordinated and suboptimal updates. To address these issues, we propose $\textbf{StructLoRA}$, a framework that tackles both limitations through a principled dual-component design: (1) an Information Bottleneck-guided filter that prunes task-irrelevant directions to mitigate semantic drift, and (2) a lightweight, training-only graph-based coordinator that enforces inter-layer consistency to resolve structural incoherence. Extensive experiments across large language models, vision language models, and vision models (including LLaMA, LLaVA, and ViT) demonstrate that $\textbf{StructLoRA}$ consistently establishes a new state of the art, outperforming not only vanilla LoRA but also advanced dynamic rank allocation and sparsity-based methods. Notably, the gains are particularly pronounced in challenging low-rank and low-data regimes. Crucially, since the proposed modules operate only during training, $\textbf{StructLoRA}$ improves performance with $\textbf{zero additional inference cost}$, shifting the focus of PEFT from mere parameter compression to a more holistic optimization of information quality and structural integrity."
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<abstract>Low-Rank Adaptation (LoRA) has become a cornerstone of parameter-efficient fine-tuning (PEFT). Yet, its efficacy is hampered by two fundamental limitations: semantic drift, arising from treating all update directions with equal importance, and structural incoherence, due to adapting layers independently, resulting in uncoordinated and suboptimal updates. To address these issues, we propose StructLoRA, a framework that tackles both limitations through a principled dual-component design: (1) an Information Bottleneck-guided filter that prunes task-irrelevant directions to mitigate semantic drift, and (2) a lightweight, training-only graph-based coordinator that enforces inter-layer consistency to resolve structural incoherence. Extensive experiments across large language models, vision language models, and vision models (including LLaMA, LLaVA, and ViT) demonstrate that StructLoRA consistently establishes a new state of the art, outperforming not only vanilla LoRA but also advanced dynamic rank allocation and sparsity-based methods. Notably, the gains are particularly pronounced in challenging low-rank and low-data regimes. Crucially, since the proposed modules operate only during training, StructLoRA improves performance with zero additional inference cost, shifting the focus of PEFT from mere parameter compression to a more holistic optimization of information quality and structural integrity.</abstract>
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%0 Conference Proceedings
%T Not All Directions Matter: Towards Structured and Task-Aware Low-Rank Model Adaptation
%A Xiao, Xi
%A Ma, Chenrui
%A Zhang, Yunbei
%A Liu, Chen
%A Wang, Zhuxuanzi
%A Li, Yanshu
%A Zhao, Lin
%A Hu, Guosheng
%A Wang, Tianyang
%A Xu, Hao
%Y Liakata, Maria
%Y Moreira, Viviane P.
%Y Zhang, Jiajun
%Y Jurgens, David
%S Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
%D 2026
%8 July
%I Association for Computational Linguistics
%C San Diego, California, United States
%@ 979-8-89176-390-6
%F xiao-etal-2026-directions
%X Low-Rank Adaptation (LoRA) has become a cornerstone of parameter-efficient fine-tuning (PEFT). Yet, its efficacy is hampered by two fundamental limitations: semantic drift, arising from treating all update directions with equal importance, and structural incoherence, due to adapting layers independently, resulting in uncoordinated and suboptimal updates. To address these issues, we propose StructLoRA, a framework that tackles both limitations through a principled dual-component design: (1) an Information Bottleneck-guided filter that prunes task-irrelevant directions to mitigate semantic drift, and (2) a lightweight, training-only graph-based coordinator that enforces inter-layer consistency to resolve structural incoherence. Extensive experiments across large language models, vision language models, and vision models (including LLaMA, LLaVA, and ViT) demonstrate that StructLoRA consistently establishes a new state of the art, outperforming not only vanilla LoRA but also advanced dynamic rank allocation and sparsity-based methods. Notably, the gains are particularly pronounced in challenging low-rank and low-data regimes. Crucially, since the proposed modules operate only during training, StructLoRA improves performance with zero additional inference cost, shifting the focus of PEFT from mere parameter compression to a more holistic optimization of information quality and structural integrity.
%U https://aclanthology.org/2026.acl-long.97/
%P 2132-2154
Markdown (Informal)
[Not All Directions Matter: Towards Structured and Task-Aware Low-Rank Model Adaptation](https://aclanthology.org/2026.acl-long.97/) (Xiao et al., ACL 2026)
ACL
- Xi Xiao, Chenrui Ma, Yunbei Zhang, Chen Liu, Zhuxuanzi Wang, Yanshu Li, Lin Zhao, Guosheng Hu, Tianyang Wang, and Hao Xu. 2026. Not All Directions Matter: Towards Structured and Task-Aware Low-Rank Model Adaptation. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 2132–2154, San Diego, California, United States. Association for Computational Linguistics.