Rethinking Fine-tuning Through Geometric Perspective

Fine-tuning pre-trained neural networks has become a cornerstone of transfer learning. However, the practical success of existing methods like low-rank adaptation (LoRA) lacks theoretical explanation. We introduce geometry-guided fine-tuning, a novel paradigm that models the fine-tuning process as the subtle movement of pre-trained weights on a low-dimensional manifold. Our approach formalizes this process through a learnable ordinary differential equation (ODE) - based framework that controls the search space of the weights, bridging existing methods with geometric principles. We empirically evaluate our method in the context of multi-task learning (MTL) fine-tuning of hierarchical vision transformers in computer vision. We propose a parameter-efficient ODE and evaluate it on the PASCAL-Context MTL benchmark. Our approach, dubbed DeLoRAoffers competitive performance across multiple dense prediction tasks, reducing trainable parameters by up to 4$\times$ compared to the best-performing baseline. This work advances both the theoretical understanding and practical application of fine-tuning, promoting efficient learning in resource-constrained environments.