Algorithmic Stability of Stochastic Gradient Descent with Momentum under Heavy-Tailed Noise
- URL: http://arxiv.org/abs/2502.00885v1
- Date: Sun, 02 Feb 2025 19:25:48 GMT
- Title: Algorithmic Stability of Stochastic Gradient Descent with Momentum under Heavy-Tailed Noise
- Authors: Thanh Dang, Melih Barsbey, A K M Rokonuzzaman Sonet, Mert Gurbuzbalaban, Umut Simsekli, Lingjiong Zhu,
- Abstract summary: We establish generalization bounds for SGD with momentum (SGDm) under heavy-tailed noise.
For quadratic loss functions, we show that SGDm admits a worse generalization bound in the presence of momentum and heavy tails.
We develop a uniform-in-time discretization error bound, which to our knowledge, is the first result of its kind for SDEs with degenerate noise.
- Score: 20.922456964393213
- License:
- Abstract: Understanding the generalization properties of optimization algorithms under heavy-tailed noise has gained growing attention. However, the existing theoretical results mainly focus on stochastic gradient descent (SGD) and the analysis of heavy-tailed optimizers beyond SGD is still missing. In this work, we establish generalization bounds for SGD with momentum (SGDm) under heavy-tailed gradient noise. We first consider the continuous-time limit of SGDm, i.e., a Levy-driven stochastic differential equation (SDE), and establish quantitative Wasserstein algorithmic stability bounds for a class of potentially non-convex loss functions. Our bounds reveal a remarkable observation: For quadratic loss functions, we show that SGDm admits a worse generalization bound in the presence of heavy-tailed noise, indicating that the interaction of momentum and heavy tails can be harmful for generalization. We then extend our analysis to discrete-time and develop a uniform-in-time discretization error bound, which, to our knowledge, is the first result of its kind for SDEs with degenerate noise. This result shows that, with appropriately chosen step-sizes, the discrete dynamics retain the generalization properties of the limiting SDE. We illustrate our theory on both synthetic quadratic problems and neural networks.
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