arXiv Machine Learning

CAST: History-Adaptive Spectral Clipping for LLM Pretraining

arXiv Machine Learning
Aug 4

GradientStabilizer:Fix the Norm, Not the Gradient

arXiv:2502. 17055v5 Announce Type: replace Abstract: Training instability in modern deep learning systems is frequently triggered by rare but extreme gradient-norm spikes, which can induce oversized parameter updates, corrupt optimizer state, and lead to slow recovery or divergence.

By Tianjin Huang, Zhangyang Wang, Haotian Hu, Zhenyu Zhang, Gaojie Jin, Xiang Li, Li Shen, Jiaxing Shang, Tianlong Chen, Ke Li, Lu Liu, Qingsong Wen, Shiwei Liu
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
Oct 26

Beyond Data Schedule: Fast LLM Pretraining on Data Mixtures by Loss-Reweighting

The paper introduces LARE, a method that adjusts domain weights during large language model pretraining by reweighting losses based on running loss statistics, rather than altering data exposure. Experiments on a 1.5B model trained with 240B tokens show that LARE improves performance across five benchmarks, achieving significant gains on GSM8K (+17.06 pp) and MATH (+9.00 pp). The approach demonstrates that balancing loss scales can enhance joint capabilities without increasing domain exposure.

By Jiazheng Li, Huaqing Zhang, Jing Xu, Tianle Cai, Jingzhao Zhang
arXiv AI
Oct 1

Foundation-Preserving Optimization in Generalized Eigenspace

The paper introduces Foundation Preserving LoRA (FoLoRA), a forgetting‑aware optimization framework that balances adaptation to downstream tasks with preservation of pretraining capabilities. FoLoRA uses a first‑order preservation condition to define a forgetting penalty based on pretraining‑proxy activations and a task utility from downstream activations, scoring update directions via a generalized Rayleigh quotient. This spectral coordinate system enables gated Adam updates that reduce low‑utility, high‑penalty directions, and the method constructs pretraining proxy calibration data by sampling from the pretrained model. Experiments on math, code, and instruction‑following tasks demonstrate that FoLoRA achieves a stronger balance between target task performance and aggregate preservation of non‑target capabilities compared to baselines.

By Dongjun Kim, Adrian de Wynter, Huancheng Chen, Heasung Kim, Haris Vikalo
arXiv Machine Learning
Sep 11

Musec: MomentUm SpEctral Clipping for Stable Muon-type Training

Musec introduces MomentUm SpEctral Clipping, an optimizer-level, architecture‑agnostic technique that replaces Muon’s spectral flattening with selective spectral clipping to stabilize training. By clipping singular values above a threshold while preserving the momentum’s spectral structure, Musec addresses loss spikes and unbounded weight growth without requiring architecture‑specific changes. Soft Musec, an efficient implementation using smooth spectral saturation via coupled Newton‑Schulz iterations, offers convergence guarantees in nonconvex nonsmooth stochastic optimization and empirically improves stability across diverse learning rates and model sizes.

By Zhuanghua Liu, Menglian Wang, Luo Luo