arXiv:2508.17169cs.LGcs.AI2025-08

将自然梯度与正交投影结合,提升持续学习的收敛性。

ONG: Orthogonal Natural Gradient Descent

  • 用自然梯度替代传统梯度,沿黎曼流形最速下降。
  • 在旋转/打乱MNIST上验证了方法有效性,但存在初始不稳定性。
  • 适合研究持续学习几何优化的学者参考。

持续学习中的正交梯度下降(OGD)虽有效,但其欧氏投影未利用问题的信息几何结构,可能导致收敛不佳。为此,本文提出结合自然梯度的正交自然梯度下降(ONG)。ONG通过高效近似的逆费雪信息矩阵(EKFAC)对每个新任务梯度进行预条件化,使更新方向遵循黎曼度量下的最速下降。为保留对先前任务的性能,ONG将这些自然梯度投影到之前任务自然梯度的正交补空间中。本文提供了该过程的初步理论依据,提出了ONG算法,并在旋转和打乱的MNIST基准上进行了初步实验。结果表明,自然梯度与正交投影的简单结合存在潜在问题,这促使未来工作聚焦于更稳健地融合几何视角,建立严格的理论基础并扩展到大规模持续学习基准。

原文摘要 · Abstract (English)

Orthogonal Gradient Descent (OGD) has emerged as a powerful method for continual learning. However, its Euclidean projections do not leverage the underlying information-geometric structure of the problem, which can lead to suboptimal convergence in learning tasks. To address this, we propose incorporating the natural gradient into OGD and present \textbf{ONG (Orthogonal Natural Gradient Descent)}. ONG preconditions each new task-specific gradient with an efficient EKFAC approximation of the inverse Fisher information matrix, yielding updates that follow the steepest descent direction under a Riemannian metric. To preserve performance on previously learned tasks, ONG projects these natural gradients onto the orthogonal complement of prior tasks' natural gradients. We provide an initial theoretical justification for this procedure, introduce the Orthogonal Natural Gradient Descent (ONG) algorithm, and present preliminary results on the Permuted and Rotated MNIST benchmarks. Our preliminary results, however, indicate that a naive combination of natural gradients and orthogonal projections has potential issues. This finding has motivated continued future work focused on robustly reconciling these geometric perspectives to develop a continual learning method, establishing a more rigorous theoretical foundation with formal convergence guarantees, and extending empirical validation to large-scale continual learning benchmarks.

持续学习自然梯度几何优化

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