arXiv:2604.23017cs.LGcs.NA2026-04

提出复数域的SGD算法,实现复杂神经网络优化并保证收敛性。

Complex Stochastic Gradient Descent and Directional Bias in Reproducing Kernel Hilbert Spaces

  • 设计复数参数更新规则,扩展SGD至复值空间。
  • 在无解析性约束下证明收敛性,支持核回归任务。
  • 可恢复超振荡函数与Blaschke乘积,适用于复数核方法。

随机梯度下降(SGD)是大规模凸优化中广泛应用的迭代方法,因其简单性和可扩展性而备受青睐。某些目标函数,如复值神经网络中的目标,可通过定义新的‘梯度’来实现复数参数的更新,从而受益于类似SGD和梯度下降(GD)的更新机制。尽管已有复数版的SGD/GD方法提出,但尚未在无需解析性假设的前提下提供收敛性保证。本文提出一种支持复数参数的SGD变体(复数SGD),并在类比实数情形的假设下建立了收敛性。值得注意的是,该结果同样适用于梯度下降(GD)。在相同假设下,我们证实了部分方向偏差结果可从实数域推广至复数域,适用于核回归问题。通过实验验证了复数SGD在利用复再生核希尔伯特空间(RKHS)进行核回归中的有效性。具体而言,当损失函数选择特定形式时,能够成功恢复来自Fock空间的超振荡函数以及来自Hardy空间的Blaschke乘积作为最优函数。

原文摘要 · Abstract (English)

Stochastic Gradient Descent (SGD) is a known stochastic iterative method popular for large-scale convex optimization problems due to its simple implementation and scalability. Some objectives, such as those found in complex-valued neural networks, benefit from updates like in SGD and Gradient Descent (GD) with a newly defined ``gradient'' that allows for complex parameters. This complex variant of the SGD/GD methods has already been proposed, but convergence guarantees without analyticity constraints have not yet been provided. We propose a variant of SGD (complex SGD) that allows for complex parameters, and we provide convergence guarantees under assumptions that parallel those from the real setting. Notably, these results extend to GD as well, and with the same set of assumptions, we confirm that some directional bias results extend from the real to the complex setting for kernel regression problems. We provide empirical results demonstrating the efficacy of the complex SGD in kernel regression problems utilizing complex reproducing kernel Hilbert spaces. In particular, we demonstrate we may recover superoscillation functions and Blaschke products from the Fock Space and Hardy Space, respectively, as the optimal functions for a particular choice of a loss function.

复数优化核方法深度学习

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