arXiv Machine Learning

The Symmetry of Differential Neural Tangent Kernel under the Orthogonal Group

The paper studies the symmetry properties of the differential neural tangent kernel (DNTK) for overparameterized physics‑informed neural networks. It shows that the infinite‑width DNTK is invariant under the orthogonal group for both two‑layer and deep networks, regardless of activation or bias. The authors further prove that integral operators induced by group‑orbit operators share spectra and that the fixed DNTK exhibits zonal symmetry on the unit sphere, enabling derivation of eigenvalue decay rates for shallow RePU networks with zero bias.

arXiv Machine Learning
Oct 8

Eigenvalues of the Hessian in Deep Learning: The Origin of Symmetry and Its Breaking

The paper investigates why Hessian spectra of trained deep learning models consistently show a bulk of eigenvalues near zero and a few isolated outliers. It proposes that these patterns arise from a hidden, highly symmetric reference configuration; when the model is perturbed (e.g., by architecture, data, or metric changes), the symmetry is broken, producing the observed cluster hierarchy. The authors analyze this mechanism in three‑layer ReLU networks and extend it to convolutional, graph, transformer models, the NTK, and related matrices such as layerwise Hessians and the Gauss‑Newton matrix.

By Yossi Arjevani
arXiv Machine Learning
Sep 15

Resolution-Independent Analysis of Encoder--Decoder Operator Learning via Limiting Kernels

The paper studies operator learning on function spaces using encoder–decoder architectures. It shows that as input and output resolutions grow, the induced kernels converge to a limiting kernel, enabling regularity assumptions independent of resolution. The authors derive upper and lower bounds for regularized stochastic gradient descent, extend the analysis to neural networks via the limiting neural tangent kernel, and provide error bounds and complexity guarantees for various kernel and encoding constructions.

By Lei Shi, Jia-Qi Yang, Ding-Xuan Zhou