Traces of Class/Cross-Class Structure Pervade Deep Learning Spectra
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Abstract (arXiv)
Numerous researchers recently applied empirical spectral analysis to the study of modern deep learning classifiers. We identify and discuss an important formal class/cross-class structure and show how it lies at the origin of the many visually striking features observed in deepnet spectra, some of which were reported in recent articles, others are unveiled here for the first time. These include spectral outliers, "spikes", and small but distinct continuous distributions, "bumps", often seen beyond the edge of a "main bulk". The significance of the cross-class structure is illustrated in three ways: (i) we prove the ratio of outliers to bulk in the spectrum of the Fisher information matrix is predictive of misclassification, in the context of multinomial logistic regression; (ii) we demonstrate how, gradually with depth, a network is able to separate class-distinctive information from class variability, all while orthogonalizing the class-distinctive information; and (iii) we propose a correction to KFAC, a well-known second-order optimization algorithm for training deepnets.
Key facts. Cited by 94 papers in the map (data through 7 Oct 2026). First posted on arXiv 27 Aug 2020.
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Citing papers per year: 2021: 8; 2022: 15; 2023: 14; 2024: 22; 2025: 7; 2026: 28.
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50 newest of 94 All 94 (JSON)
- 2021Gradient Descent on Neural Networks Typically Occurs at the Edge of Stabilitycited by 413
- 2023Fine-Tuning Language Models with Just Forward Passescited by 337
- 2021A Geometric Analysis of Neural Collapse with Unconstrained Featurescited by 226
- 2024Adam-mini: Use Fewer Learning Rates To Gain Morecited by 134
- 2024Why Transformers Need Adam: A Hessian Perspectivecited by 123
- 2022Extended Unconstrained Features Model for Exploring Deep Neural Collapsecited by 101
- 2022Inducing Neural Collapse in Imbalanced Learning: Do We Really Need a Learnable Classifier at the End of Deep Neural Network?cited by 100
- 2022On the Optimization Landscape of Neural Collapse under MSE Loss: Global Optimality with Unconstrained Featurescited by 97
- 2022Are All Losses Created Equal: A Neural Collapse Perspectivecited by 78
- 2022Neural Collapse with Normalized Features: A Geometric Analysis over the Riemannian Manifoldcited by 50
- 2022A Simple Approach to Improve Single-Model Deep Uncertainty via Distance-Awarenesscited by 49
- 2023Generalized Neural Collapse for a Large Number of Classescited by 39
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- 2026Understanding the Subspace Stabilization of the Hessian and Gradient Covariance Matrix25 Sep 2026
- 2026Communication-Efficient LLM Adaptation over Decentralized GPU Meshes13 Sep 2026
- 2026The Multiple Timescales of Gradient Descent on the Edge of Stability: A Perturbative Derivation of the Central Flow1 Sep 2026
- 2026Layers Matter: Why Continual Learning Regularization Should Be Layer-Adaptive16 Aug 2026
- 2026Mini-batch Noise Lowers Sharpness via Dominant-Subspace Fluctuations25 Jul 2026
- 2026A Defense of the Quadratic Model23 Jul 2026
- 2026Functional Equivalence and Geometric Diversity in Neural Network Approximations: An Empirical Characterization21 Jul 2026
- 2026Explaining Near-Zero Hessian Eigenvalues Through Approximate Symmetries in Neural Networks8 Jul 2026
- 2026Gradient Smoothing: Coupling Layer-wise Updates for Improved Optimization29 Jun 2026
- 2026Closed-Form Steepest Descent Direction toward Flat Minima: Reducing Upper Bounds on the Loss Hessian Eigenspectrum in Neural Networks27 Jun 2026
- 2026Algebraic Dead Directions in LayerNorm Transformers: A Forward-Pass-Only Diagnostic at LLM Scale17 Jun 2026
- 2026Inconsistency-Aware Minimization: Improving Generalization with Unlabeled Data29 May 2026
12 newest of 92 All 92 (JSON)