arXiv Statistics ML

The Impact of Anisotropic Covariance Structure on the Training Dynamics and Generalization Error of Linear Networks

arXiv Machine Learning
Oct 22

Silent Alignment in Two-Layer Linear Networks: A High-Dimensional Perspective

The paper analyzes gradient flow in a two‑layer linear neural network as the input, hidden, and output dimensions grow proportionally. Using a closed‑form solution combined with random matrix theory, it derives exact asymptotic spectral distributions for the weight matrices at all times and tracks how the learned subspace evolves. In the limit of small initialization, the study reveals a silent alignment phase where singular directions align quickly while singular values and loss stay unchanged, followed by a visible learning phase on a logarithmic timescale where singular values increase and loss decreases through a saddle‑to‑saddle dynamic that becomes continuous in the high‑dimensional limit.

By Simon Martin (DI-ENS, LPENS, SIERRA), Francis Bach (DI-ENS, SIERRA), Giulio Biroli (LPENS)
arXiv Machine Learning
Sep 25

Pointwise Generalization in Deep Neural Networks

The paper introduces a pointwise generalization theory for fully connected deep neural networks, using a pointwise Riemannian Dimension derived from eigenvalues of learned feature representations across layers. This framework provides hypothesis-dependent, representation-aware generalization bounds that are significantly tighter than traditional size- or norm-based approaches, both theoretically and experimentally. The authors analytically identify structural properties that explain deep networks’ tractability and empirically show that the pointwise Riemannian Dimension captures feature compression, over‑parameterization effects, and optimizer bias.

By Shaojie Li, Yunbei Xu
arXiv AI
Jun 29

Derivation of effective gradient flow equations and dynamical truncation of training data in Deep Learning

arXiv:2501. 07400v2 Announce Type: replace-cross Abstract: We derive explicit equations governing the cumulative biases and weights in Deep Learning with ReLU activation function, based on gradient descent for the Euclidean loss in the input layer, and under the assumption that the weights are, in a precise sense, adapted to the coordinate system distinguished by the activations.

By Thomas Chen