arXiv Machine Learning

OPLoRA: Orthogonal Projection LoRA Prevents Catastrophic Forgetting during Parameter-Efficient Fine-Tuning

arXiv AI
Oct 16

Towards Continual Learning: Mitigating Forgetting With Subspace Tuning

The paper introduces Subspace Tuning (SST), a fine‑tuning technique that restricts weight updates to the bottom singular subspace of model parameters, thereby protecting the principal directions that are most prone to catastrophic forgetting. SST is optimizer‑agnostic, works with existing fine‑tuning recipes such as SFT and self‑distillation, and includes dense gradient estimation and a refresh mechanism to enhance learning. Experiments show that SST can preserve up to 99 % of the weight subspace, significantly reduce KL drift, and nearly eliminate forgetting in large‑scale language models while maintaining strong target‑task performance.

By Arnav Chavan, Kusha Sareen, Rishabh Tiwari, Abhranil Chandra, Johan Obando-Ceron, Kurt Keutzer, Scott Niekum, Inderjit S Dhillon, Devvrit Khatri
arXiv Machine Learning
Oct 15

Task-Driven Subspace Decomposition for Knowledge Sharing and Isolation in LoRA-based Continual Learning

The paper introduces LoDA, a LoRA-based continual learning method that decomposes update spaces into task‑shared and truly task‑specific subspaces using energy‑based objectives. By fixing down‑projections and learning up‑projections with Gradient‑Aligned Optimization, LoDA recalibrates general updates in closed form after each task, aiming to improve knowledge sharing and isolation. Experiments show that LoDA outperforms existing CL methods.

By Lingfeng He, De Cheng, Huaijie Wang, Xi Yang, Nannan Wang, Xinbo Gao
Hugging Face Trending Papers
Oct 15

Towards Continual Learning: Mitigating Forgetting With Subspace Tuning

The paper introduces Subspace Tuning (SST), a fine‑tuning technique that confines weight updates to the bottom singular subspace of model parameters, thereby avoiding changes along principal directions that cause catastrophic forgetting. SST is optimizer‑agnostic, works with existing fine‑tuning recipes, and includes dense gradient estimation and a refresh mechanism. Experiments show that protecting up to 99% of the weight subspace significantly reduces forgetting, improves retention, and maintains strong target‑task performance, especially in large‑model regimes, while also reducing KL drift by 2–4× compared to baseline methods.

arXiv Statistics ML
Oct 2

ChainLoRA: Geometry-Preserving Task Vector Merging for Continual Learning in LLMs

ChainLoRA is a replay‑free continual learning framework for large language models that merges task vectors while preserving geometry. It uses chain‑updated training with a one‑sided orthogonality proxy to keep historical state and regularization overhead constant, and applies post‑stream adaptive SVD merging with Procrustes adaptation to separate shared and task‑specific components. Experiments demonstrate state‑of‑the‑art performance on Large and SuperNI benchmarks and competitive results on Standard CL, approaching the scores of replay‑based methods.

By Hang Yin, Haozhe Wang, Yuhua Luo, Zhangqi Pan, Xiaoxing Wang, Junchi Yan
Hugging Face Trending Papers
Oct 29

Preserving Utility in Continual LLM Unlearning via Orthogonal Projections

The paper introduces Continual Orthogonal Projection (COP), a gradient‑projection method that limits each unlearning update to the orthogonal complement of previously cached activation subspaces, thereby preventing interference between successive deletions. COP requires only a low‑rank basis per layer, avoiding the need for past gradients or previous forget sets, and can be applied to any differentiable‑loss unlearning method without altering its objective. Experiments on TOFU and RWKU benchmarks demonstrate that COP maintains model utility across sequential unlearning requests while preserving forgetting effectiveness and preventing collapse of standard objectives.