arXiv Machine Learning
Sep 24

The Drift Contract: Spectral Updates for Depth-Robust Local Learning

The paper introduces the Drift Contract, a spectral update geometry for local learning that improves depth robustness and hyperparameter stability. By applying momentum orthogonalization with spectral step scaling to per‑layer updates, the authors achieve consistent performance across a wide range of widths and depths on CIFAR‑10 MLPs, outperforming local Adam and providing a per‑layer, input‑conditioned drift bound. The study also shows that the spectral geometry itself, rather than step‑size rules, drives the observed depth robustness, while a negative result indicates that the stability benefit is limited to non‑normalized layers.

By Fabien Polly
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 AI
Oct 7

Does Muon Need Fine-Grained Spectral Shaping?

The paper investigates how much spectral detail is necessary for the Muon optimizer, which traditionally uses a flat spectral profile. By analyzing singular modes, the authors find that most modes lie below a noise edge yet align positively with the gradient, leading them to propose BulkBoost—a two‑band spectral reweighting framework that adjusts bulk and spike gains while preserving matrix norms. Experiments across various pre‑training settings show that this low‑dimensional reweighting matches or surpasses fine‑grained spectral profiles, achieving notable loss reductions.

By Meher Chaitanya, Tianyi Zhou, Aristides Gionis
arXiv AI
Aug 25

A Physical Response-and-Memory Model for Muon Optimization

The paper introduces a physical response-and-memory model for the Muon optimizer, explaining its semi‑orthogonalized momentum update as the maximally dissipative direction under an output‑side safety budget. It treats the weight matrix as a responsive medium with internal stress, showing that momentum corresponds to accumulated stress whose relaxation occurs over multiple timescales—fast and slow. Based on this, the authors propose the Bi‑Maxwell optimizer, which uses a two‑timescale memory kernel and achieves target loss in fewer steps on a public large‑language‑model benchmark.

By Yinze Hu, Hongjun Xiang, Xingao Gong, Hongyu Yu