The Persistence of Neural Collapse Despite Low-Rank Bias
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Abstract (arXiv)
Neural collapse (NC) and its multi-layer variant, deep neural collapse (DNC), describe a structured geometry that occurs in the features and weights of trained deep networks. Recent theoretical work by Sukenik et al. using a deep unconstrained feature model (UFM) suggests that DNC is suboptimal under mean squared error (MSE) loss. They heuristically argue that this is due to low-rank bias induced by L2 regularization. In this work, we extend this result to deep UFMs trained with cross-entropy loss, showing that high-rank structures, including DNC, are not generally optimal. We characterize the associated low-rank bias, proving a fixed bound on the number of non-negligible singular values at global minima as network depth increases. We further analyze the loss surface, demonstrating that DNC is more prevalent in the landscape than other critical configurations, which we argue explains its frequent empirical appearance. Our results are validated through experiments in deep UFMs and deep neural networks.
Key facts. Cited by 12 papers in the map (data through 7 Oct 2026). Builds on 72 of its 86 references that are in the map. First posted on arXiv 30 Oct 2024.
Builds on
72 of 86 references.
References · 72
- 2020Prevalence of Neural Collapse during the terminal phase of deep learning trainingcited by 713
- 2017Sharp Minima Can Generalize For Deep Netscited by 462
- 2019Implicit Regularization in Deep Matrix Factorizationcited by 402
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- 2014The Loss Surfaces of Multilayer Networkscited by 278
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- 2021A Geometric Analysis of Neural Collapse with Unconstrained Featurescited by 226
- 2018Gradient Descent Happens in a Tiny Subspacecited by 208
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38 more
- 2016Eigenvalues of the Hessian in Deep Learning: Singularity and Beyondcited by 156
- 2021Neural Collapse Under MSE Loss: Proximity to and Dynamics on the Central Pathcited by 156
- 2021The Low-Rank Simplicity Bias in Deep Networkscited by 150
- 2020Towards Resolving the Implicit Bias of Gradient Descent for Matrix Factorization: Greedy Low-Rank Learningcited by 148
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- 2022Extended Unconstrained Features Model for Exploring Deep Neural Collapsecited by 101
- 2021On the Role of Neural Collapse in Transfer Learningcited by 100
- 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
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- 2020Traces of Class/Cross-Class Structure Pervade Deep Learning Spectracited by 94
- 2021An Unconstrained Layer-Peeled Perspective on Neural Collapsecited by 87
- 2022On the Implicit Bias in Deep-Learning Algorithmscited by 84
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- 2022Imbalance Trouble: Revisiting Neural-Collapse Geometrycited by 80
- 2022Are All Losses Created Equal: A Neural Collapse Perspectivecited by 78
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- 2022Limitations of Neural Collapse for Understanding Generalization in Deep Learningcited by 63
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- 2022Neural Collapse with Normalized Features: A Geometric Analysis over the Riemannian Manifoldcited by 50
- 2023Deep Neural Collapse Is Provably Optimal for the Deep Unconstrained Features Modelcited by 43
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- 2022A Law of Data Separation in Deep Learningcited by 36
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- 2024Average gradient outer product as a mechanism for deep neural collapsecited by 21
50 most cited of 72 All 72 (JSON)
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Citing papers per year: 2025: 4; 2026: 8.
12 papers.
- 2025Neural Collapse is Globally Optimal in Deep Regularized ResNets and Transformerscited by 9
- 2025MaxSup: Overcoming Representation Collapse in Label Smoothingcited by 4
- 2026Grokking or Glitching? How Low-Precision Drives Slingshot Loss Spikescited by 4
- 2025Diagonalizing the Softmax: Hadamard Initialization for Tractable Cross-Entropy Dynamicscited by 2
- 2026Neural Collapse Dynamics: Depth, Activation, Regularisation, and Feature Norm Thresholdcited by 2
- 2026Structure Before Collapse: Transient semantic geometry in next-token predictioncited by 2
- 2026Why Loss Re-weighting Works If You Stop Early: Training Dynamics of Unconstrained Featurescited by 1
- 2026The Implicit Bias of Logit Regularizationcited by 1
- 2026Optimizer choice matters for the emergence of Neural Collapsecited by 1
- 2025Sharper Convergence Rates for Nonconvex Optimisation via Reduction Mappingscited by 0
- 2026PLATE: Plasticity-Tunable Efficient Adapters for Geometry-Aware Continual Learningcited by 0
- 2026The Implicit Bias of Depth: From Neural Collapse to Softmax Codescited by 0
- 2026Structure Before Collapse: Transient semantic geometry in next-token prediction25 Jun 2026
- 2026The Implicit Bias of Depth: From Neural Collapse to Softmax Codes21 May 2026
- 2026Grokking or Glitching? How Low-Precision Drives Slingshot Loss Spikes7 May 2026
- 2026Neural Collapse Dynamics: Depth, Activation, Regularisation, and Feature Norm Threshold31 Mar 2026
- 2026Optimizer choice matters for the emergence of Neural Collapse18 Feb 2026
- 2026The Implicit Bias of Logit Regularization12 Feb 2026
- 2026PLATE: Plasticity-Tunable Efficient Adapters for Geometry-Aware Continual Learning3 Feb 2026
- 2026Why Loss Re-weighting Works If You Stop Early: Training Dynamics of Unconstrained Features17 Jan 2026
- 2025Diagonalizing the Softmax: Hadamard Initialization for Tractable Cross-Entropy Dynamics3 Dec 2025
- 2025Sharper Convergence Rates for Nonconvex Optimisation via Reduction Mappings10 Jun 2025
- 2025Neural Collapse is Globally Optimal in Deep Regularized ResNets and Transformers21 May 2025
- 2025MaxSup: Overcoming Representation Collapse in Label Smoothing18 Feb 2025