arXiv:2505.19527cs.LGcs.AI2025-05

用滚动球模拟优化,让模型避开数据噪声干扰。

Rolling Ball Optimizer: Learning by ironing out loss landscape wrinkles

  • 模拟小球在损失曲面滚动,全局感知地形而非局部梯度
  • 在MNIST和CIFAR上收敛更快,准确率更高,泛化性能更好
  • 适合对噪声敏感的高维神经网络训练场景

训练大型神经网络需要优化高维、依赖数据的损失函数。这些函数的优化景观通常极为复杂且纹理繁复,甚至呈分形特征,包含大量伪局部极小值、病态山谷、退化点和鞍点。更复杂的是,这些景观特性取决于数据本身,训练数据中的噪声会传播并导致不具代表性的微观结构。这使基于梯度的优化方法(依赖局部几何)易受噪声干扰,导致优化动态对数据噪声高度敏感,进而影响泛化性能。为此,我们提出一种新优化方法:滚动球优化器(RBO),通过引入更大区域的损失景观信息,打破空间局部性。该方法模拟一个具有有限半径的刚性球在损失曲面上滚动,是梯度下降的自然推广——在半径趋于零时即退化为梯度下降。半径作为超参数,控制算法感知景观的尺度,从而调节其交互粒度。我们基于直觉:大尺度景观比精细结构更少依赖数据且更易优化,进一步证明该算法对损失函数具有平滑效应。在MNIST和CIFAR-10/100上的实验表明,相比SGD、SAM和熵随机梯度下降(Entropy-SGD),RBO在收敛速度、训练精度和泛化性能方面均表现优异。

原文摘要 · Abstract (English)

Training large neural networks (NNs) requires optimizing high-dimensional data-dependent loss functions. The optimization landscape of these functions is often highly complex and textured, even fractal-like, with many spurious local minima, ill-conditioned valleys, degenerate points, and saddle points. Complicating things further is the fact that these landscape characteristics are a function of the data, meaning that noise in the training data can propagate forward and give rise to unrepresentative small-scale geometry. This poses a difficulty for gradient-based optimization methods, which rely on local geometry to compute updates and are, therefore, vulnerable to being derailed by noisy data. In practice,this translates to a strong dependence of the optimization dynamics on the noise in the data, i.e., poor generalization performance. To remediate this problem, we propose a new optimization procedure: Rolling Ball Optimizer (RBO), that breaks this spatial locality by incorporating information from a larger region of the loss landscape in its updates. We achieve this by simulating the motion of a rigid sphere of finite radius rolling on the loss landscape, a straightforward generalization of Gradient Descent (GD) that simplifies into it in the infinitesimal limit. The radius serves as a hyperparameter that determines the scale at which RBO sees the loss landscape, allowing control over the granularity of its interaction therewith. We are motivated by the intuition that the large-scale geometry of the loss landscape is less data-specific than its fine-grained structure, and that it is easier to optimize. We support this intuition by proving that our algorithm has a smoothing effect on the loss function. Evaluation against SGD, SAM, and Entropy-SGD, on MNIST and CIFAR-10/100 demonstrates promising results in terms of convergence speed, training accuracy, and generalization performance.

优化器损失曲面泛化

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