Implicit Bias of Diagonal Linear Networks Explained by L1 Norm

Jiajie Zhao, Jianxing Wang, Junjie Yang, Zhiwei Bai, Yaoyu Zhang· July 15, 2026 View original

Summary

This study extends previous work to show that the gradient flow dynamics of deep and two-layer diagonal linear networks, under infinitesimal initialization, can be characterized by a specific algorithm. This algorithm converges to a solution of a modified L1 norm minimization problem, establishing that the implicit bias of these networks corresponds to this modified L1 norm.

This research investigates the gradient flow dynamics of diagonal linear networks, specifically focusing on both deep and a broader class of two-layer architectures, when initialized infinitesimally. Building upon prior work, the study demonstrates that the training trajectories of these networks can be precisely described by a newly proposed algorithm. A key finding is that this algorithm consistently converges to the solution of a modified L1 norm minimization problem. This convergence establishes a crucial insight: the implicit bias inherent in both deep and two-layer diagonal linear networks, under infinitesimal initialization, directly corresponds to this modified L1 norm. Furthermore, the study sheds light on the underlying mechanisms driving these dynamics by identifying the Structural Invariant Manifold (SIM) as a critical geometric structure. The SIM plays a pivotal role in shaping the learning process, providing a deeper understanding of how these networks arrive at their solutions.

Why it matters

Understanding the implicit bias of neural networks is fundamental for predicting their behavior, improving generalization, and designing more robust and interpretable AI models, especially in the context of deep learning theory.

How to implement this in your domain

  1. 1Review the theoretical underpinnings of implicit bias in neural networks relevant to your model architectures.
  2. 2Consider how L1 norm minimization principles might influence the sparsity or feature selection in your models.
  3. 3Investigate the impact of initialization strategies on the implicit bias and generalization performance of your networks.
  4. 4Apply insights into gradient flow dynamics to better understand and debug training processes for linear networks.
  5. 5Explore the concept of Structural Invariant Manifolds to analyze the geometric structures shaping your model's learning.

Who benefits

AI/ML ResearchData ScienceSoftware DevelopmentFinancial Modeling

Key takeaways

  • The gradient flow dynamics of diagonal linear networks can be characterized by a specific algorithm.
  • This algorithm converges to a modified L1 norm minimization problem.
  • The implicit bias of these networks, under infinitesimal initialization, corresponds to a modified L1 norm.
  • The Structural Invariant Manifold is a key geometric structure shaping the learning process.

Original post by Jiajie Zhao, Jianxing Wang, Junjie Yang, Zhiwei Bai, Yaoyu Zhang

"arXiv:2607.12332v1 Announce Type: new Abstract: We study the gradient flow dynamics of diagonal linear networks for regression tasks under infinitesimal initialization. Extending Theorem 1 from Pesme & Flammarion (2023), we generalize the analysis to both deep diagonal linear net…"

View on X

Originally posted by Jiajie Zhao, Jianxing Wang, Junjie Yang, Zhiwei Bai, Yaoyu Zhang on X · view source

Want to go deeper?

Turn these trends into skills with Learnijoy's hands-on AI & tech courses.

Explore courses