只取所需:秩最小化作为持续学习中的隐式遗忘正则化器
Take Only What You Need: Rank Minimization as an Implicit Forgetting Regularizer in Continual Learning
AI总结:
本文提出CoDyRA方法,通过秩最小化作为隐式遗忘正则化器,在持续学习中平衡可塑性与稳定性,在多个基准上优于现有方法。
摘要:
持续学习中的核心张力是可塑性(获取新知识)与稳定性(保留先前知识)之间的权衡。我们研究如何通过容量控制(即调节每次参数更新的有效秩,这是LoRA更新中可直接控制的逐步骤量)来持续更新预训练骨干网络,使其吸收新知识的同时保留现有能力。对模块和任务间LoRA秩和放置的受控探测揭示了一致的权衡,存在一个随放置和任务变化的中等秩最佳点,没有普遍最优的固定秩;一个形式化界限表明遗忘随秩增长。基于这些发现,我们提出了持续动态秩选择LoRA(CoDyRA),该方法通过在每个组件重要性权重上施加稀疏性促进正则化,联合训练每个LoRA更新与秩最小化。监督目标驱动可塑性;秩最小化正则化遗忘。我们证明秩最小化在持续学习机制中充当隐式遗忘正则化器,通过控制相对于当前模型状态的遗忘,同时保护通用能力和先前任务知识。在MTIL、X-TAIL和TRACE(CLIP、LLaMA、Gemma)上,CoDyRA在新知识学习和遗忘方面优于先前的持续学习方法,实现了强大的可塑性-稳定性平衡。代码可在https://github.com/jeff024/codyra获取。
英文摘要:
The central tension in continual learning (CL) is the trade-off between plasticity (acquiring new knowledge) and stability (retaining prior knowledge). We study how a pre-trained backbone can be continually updated to absorb new knowledge while preserving existing capabilities, via capacity control: regulating the effective rank of each parameter update, a per-step quantity directly controllable inside a LoRA update. A controlled probe of LoRA rank and placement across modules and tasks reveals a consistent trade-off, with a moderate-rank sweet spot that varies by placement and task, leaving no universally optimal fixed rank; a formal bound shows forgetting grows with rank. Building on these findings, we propose Continual Dynamic Rank-Selective LoRA (CoDyRA), which jointly trains each LoRA update with rank minimization via sparsity-promoting regularization on per-component importance weights. The supervised objective drives plasticity; rank minimization regularizes forgetting. We show that rank minimization serves as an implicit forgetting regularizer in the CL regime, protecting general capability and prior-task knowledge simultaneously by controlling forgetting against the current model state. Across MTIL, X-TAIL, and TRACE (CLIP, LLaMA, Gemma), CoDyRA outperforms prior CL methods on new knowledge learning and forgetting, achieving a strong plasticity-stability balance. Project page: https://artificer-ai-lab.github.io/CoDyRA.
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