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arXiv 2603.26299cs.CVcs.AIcs.LG
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偏好对齐的LoRA融合:保持子空间覆盖与解决方向各向异性

Preference-Aligned LoRA Merging: Preserving Subspace Coverage and Addressing Directional Anisotropy

KAIST(韩国科学技术院)

Wooseong Jeong, Wonyoung Lee, Kuk-Jin Yoon

AI总结:

本文提出TARA-Merging方法,通过偏好加权交叉熵伪损失对齐融合权重,保持任务相关LoRA子空间,提升子空间覆盖和缓解各向异性,实验显示优于基线方法。

摘要:

合并多个低秩适应(LoRA)模块有助于构建通用系统,但挑战在于LoRA更新方向跨度不同子空间且贡献不均。简单合并会导致某些任务损失关键方向被削弱,而次要方向被过度强调,降低模型对所有任务的表示能力。本文从子空间覆盖和各向异性两个角度重新审视该问题,提出TARA-Merging(任务-秩各向异性对齐),通过偏好加权交叉熵伪损失对齐融合权重并保留任务相关的LoRA子空间。这确保了广泛的子空间覆盖并通过方向重加权缓解各向异性。在八个视觉和六个NLI基准测试中,TARA-Merging一致优于普通和LoRA-aware基线,展示了强大的鲁棒性和泛化能力,并突显了在LoRA融合中解决子空间覆盖和各向异性的重要性。

英文摘要:

Merging multiple Low-Rank Adaptation (LoRA) modules is promising for constructing general-purpose systems, yet challenging because LoRA update directions span different subspaces and contribute unevenly. When merged naively, such mismatches can weaken the directions most critical to certain task losses while overemphasizing relatively less important ones, ultimately reducing the model's ability to represent all tasks faithfully. We revisit this problem through two perspectives: subspace coverage, which captures how broadly LoRA directions cover diverse representational directions, and anisotropy, which reflects the imbalance of influence across those directions. We propose TARA-Merging (Task-Rank Anisotropy Alignment), which aligns merging weights using a preference-weighted cross-entropy pseudo-loss while preserving task-relevant LoRA subspaces. This ensures broad subspace coverage and mitigates anisotropy via direction-wise reweighting. Across eight vision and six NLI benchmarks, TARA-Merging consistently outperforms vanilla and LoRA-aware baselines, demonstrating strong robustness and generalization, and highlighting the importance of addressing both subspace coverage and anisotropy in LoRA merging.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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