arXiv:2603.28956math.FAcs.LG2026-03

揭示非内积范数下最小范数插值的泛化边界,突破传统假设限制。

Minimum Norm Interpolation via the Local Theory of Banach Spaces: The Role of $2$-Uniform Convexity

  • 基于2-一致凸性假设,推导出线性与非线性模型中最小范数插值的偏差上界
  • 在亚高斯协变量和各向同性单位球条件下,该上界可达到最优
  • 首次为非高斯、非内积范数情形下的ℓ_p最小范数插值提供精确泛化界

最小范数插值(MNI)框架近年来被广泛用于理解过参数化模型(如神经网络)的泛化能力。本文在2-一致凸性假设下研究MNI,该条件弱于要求范数由内积诱导;在此设定下,MNI通常无闭式解。我们证明该条件能给出线性与非线性模型中MNI偏差的上界。进一步表明,当范数单位球处于各向同性或John位置,且协变量为i.i.d.子高斯分布时(例如分量独立取±1的Rademacher分布),此上界是紧的。此外,在相同协变量假设下,我们证明了当p ∈ (1 + C/log d, 2]时,ℓ_p-MNI的泛化误差存在紧界。据我们所知,这是首个在非高斯协变量且范数非内积诱导情形下建立紧泛化界的工作。本研究受经典K-凸性理论及近期关于2-一致凸与各向同性凸体几何研究的启发。

原文摘要 · Abstract (English)

The minimum-norm interpolator (MNI) framework has recently attracted considerable attention as a tool for understanding generalization in overparameterized models, such as neural networks. In this work, we study the MNI under a $2$-uniform convexity assumption, which is weaker than requiring the norm to be induced by an inner product; in this setting, the MNI typically does not admit a closed-form solution. At a high level, we show that this condition yields an upper bound on the MNI bias in both linear and nonlinear models. We further show that this bound is sharp for overparameterized linear regression when the norm's unit ball is in isotropic or John's position and the covariates are i.i.d.\ sub-Gaussian, for example, when each covariate vector has i.i.d. Rademacher entries. Finally, under the same assumption on the covariates, we prove sharp generalization bounds for the $\ell_p$-MNI when $p \in \bigl(1 + C/\log d, 2\bigr]$. To the best of our knowledge, this is the \emph{first} work to establish sharp bounds for non-Gaussian covariates in linear models when the norm is not induced by an inner product. This work is deeply inspired by classical work on $K$-convexity and recent work on the geometry of $2$-uniformly convex and isotropic convex bodies.

泛化分析最小范数凸几何机器学习理论

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