将低秩微调扩展到高维参数空间,保持结构一致性
Generalized Tensor-based Parameter-Efficient Fine-Tuning via Lie Group Transformations
- 把参数看作李群元素,用李代数扰动实现平滑更新
- 在视觉与语言任务上均超越现有方法,提升显著
- 适合需要高效微调高维模型的研究者
将预训练基础模型适配至多样下游任务是人工智能的核心实践。然而,任务多样性与高昂计算成本使得全量微调不切实际。为此,参数高效微调(PEFT)方法如LoRA应运而生,成为研究热点。尽管成效显著,现有方法主要针对线性层设计,聚焦二维矩阵,却忽视了卷积核等高维参数空间。直接将其应用于高维空间常破坏其内在结构关系。面对矩阵型PEFT的快速发展,我们提出一种通用化方法,将矩阵型PEFT推广至高维参数空间,同时保持其结构特性。具体而言,将参数视为李群元素,更新通过对应的李代数扰动建模,并经指数映射回李群,确保更新过程平滑且一致,保留参数空间的固有结构。在计算机视觉与自然语言处理任务上的大量实验验证了该方法的有效性与通用性,显著优于现有方法。
原文摘要 · Abstract (English)
Adapting pre-trained foundation models for diverse downstream tasks is a core practice in artificial intelligence. However, the wide range of tasks and high computational costs make full fine-tuning impractical. To overcome this, parameter-efficient fine-tuning (PEFT) methods like LoRA have emerged and are becoming a growing research focus. Despite the success of these methods, they are primarily designed for linear layers, focusing on two-dimensional matrices while largely ignoring higher-dimensional parameter spaces like convolutional kernels. Moreover, directly applying these methods to higher-dimensional parameter spaces often disrupts their structural relationships. Given the rapid advancements in matrix-based PEFT methods, rather than designing a specialized strategy, we propose a generalization that extends matrix-based PEFT methods to higher-dimensional parameter spaces without compromising their structural properties. Specifically, we treat parameters as elements of a Lie group, with updates modeled as perturbations in the corresponding Lie algebra. These perturbations are mapped back to the Lie group through the exponential map, ensuring smooth, consistent updates that preserve the inherent structure of the parameter space. Extensive experiments on computer vision and natural language processing validate the effectiveness and versatility of our approach, demonstrating clear improvements over existing methods.
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