arXiv Machine Learning

Dynamics of Stochastic Momentum with Sparse Updates in High Dimensions

The paper studies momentum-based optimization when updates are sparse, focusing on two tractable models: a least‑squares problem with sparse inputs and a logistic regression problem with a rare class. It derives exact closed‑form second‑moment dynamics and analyzes their high‑dimensional limits across three scaling exponents for sparsity, batch size, and momentum decay. The resulting phase diagram is governed by the ratio of a momentum retention timescale and a learning timescale, revealing regimes where the dynamics match SGD, become unstable, or recover classical heavy‑ball behavior, and showing that oscillatory behavior depends on token sparsity, leading to a spectral conflict for global momentum.

Hugging Face Trending Papers
Sep 2

Momentum in large-batch training: Polyak enlarges the critical batch size, Nesterov improves data efficiency

The paper investigates how momentum methods affect large‑batch training in a one‑pass setting using power‑law kernel regression. It derives critical learning rates for SGD, Polyak, and Nesterov, and shows how these rates depend on batch size, momentum, and model capacity. The authors provide scaling laws for risk dynamics, a three‑regime batch‑size phase diagram, and demonstrate that Polyak increases the critical batch size while Nesterov improves data efficiency in the large‑batch regime.

arXiv Machine Learning
Sep 3

Momentum in large-batch training: Polyak enlarges the critical batch size, Nesterov improves data efficiency

The paper investigates how momentum methods affect large‑batch training in a one‑pass setting using power‑law kernel regression. It derives critical learning rates for SGD, Polyak, and Nesterov, and shows how these rates depend on batch size, momentum, and a capacity exponent. The authors then analyze risk dynamics, optimize final‑step risk under a fixed data budget, and present a three‑regime batch‑size phase diagram that highlights Polyak’s ability to enlarge the critical batch size and Nesterov’s superior data efficiency in the large‑batch regime.

By Jia-Nan Wang, Zixun Huang, Kairui Li, Lei Wu
arXiv Machine Learning
Sep 23

A Spectral Theory of Grokking: Weight Decay induces Feature Learning

The paper presents a spectral theory explaining the phenomenon of grokking, where an initial fit to training data is followed by a delayed improvement in generalization. It shows that for homogeneous networks trained with squared loss and L₂ weight decay, residuals after memorization influence the neural tangent kernel (NTK) dynamics, leading to a transition from lazy to rich learning. The theory predicts that grokking timescales depend on the product of learning rate and weight decay, and that stronger decay can halt fitting, with empirical validation on modular addition tasks using MLPs and Transformers.

By Lenz Pracher, Pascal de Jong, Oskar Lieshaus, Alan Jeffares, Steffen Rulands
arXiv AI
Jun 4

Spectral Scaling Laws of Muon

arXiv:2606. 04058v1 Announce Type: cross Abstract: Orthonormalized update rules have rapidly become a leading choice of optimizer for training large language models, with recent open-source state-of-the-art models adopting Muon.

By Gagik Magakyan, Pablo Parrilo, Asuman Ozdaglar
arXiv Machine Learning
Sep 4

High-Dimensional Learning Dynamics of Attention-Indexed Models

The paper investigates the training dynamics of attention mechanisms in high-dimensional settings, focusing on attention-indexed models that encompass multi-layer and multi-head architectures. It shows that while the loss landscape can be described by a finite set of trace order parameters, the online stochastic gradient descent dynamics involve an infinite hierarchy of matrix moments that can be accurately approximated by a finite truncated system. The study further reveals that the choice of attention parameterization acts as an implicit bias: untied attention can get trapped in uninformative states, whereas tied attention induces symmetry breaking and enables weak recovery with θ(d² log d) samples, and untied attention exhibits a fast-slow dynamic leading to weak recovery when symmetry is broken.

By Yizhou Xu, Margarita Sagitova, Lenka Zdeborov\'a, Florent Krzakala
arXiv Machine Learning
Sep 11

Quantifying the Memorization-to-Generalization Transition: Scaling Laws and Phase Structure in Grokking

The study investigates the delayed transition from memorization to generalization—known as grokking—in two‑hidden‑layer MLPs trained on modular arithmetic. By exploring 384 hyperparameter configurations, the authors derive a power‑law scaling relation for the onset time of generalization, showing that data complexity dominates over model capacity. A clear phase boundary at weight decay around 1.0 separates grokking from non‑grokking regimes, and weight norm trajectories indicate implicit regularization during the transition.

By Anish Kataria