Paper · Sep 26, 2025

Neural Feature Geometry Evolves as Discrete Ricci Flow

Moritz Hehl, Max von Renesse, Melanie Weber

As on arXiv

Abstract

Deep neural networks learn feature representations via complex geometric transformations of the input data manifold. Despite the models' empirical success across domains, our understanding of neural feature representations is still incomplete. In this work we investigate neural feature geometry through the lens of discrete geometry. Since the input data manifold is typically unobserved, we approximate it using geometric graphs that encode local similarity structure. We provide theoretical results on the evolution of these graphs during training, showing that nonlinear activations play a crucial role in shaping feature geometry in feedforward neural networks. Moreover, we discover that the geometric transformations resemble a discrete Ricci flow on these graphs, suggesting that neural feature geometry evolves analogous to Ricci flow. This connection is supported by experiments on over 20,000 feedforward neural networks trained on binary classification tasks across both synthetic and real-world datasets. We observe that the emergence of class separability corresponds to the emergence of community structure in the associated graph representations, which is known to relate to discrete Ricci flow dynamics. Building on these insights, we introduce a novel framework for locally evaluating geometric transformations through comparison with discrete Ricci flow dynamics. Our results suggest practical design principles, including a geometry-informed early-stopping heuristic and a criterion for selecting network depth.

Submitted
Sep 26, 2025
Subjects
cs.LG, cs.DM, math.DG

Comments: 38 pages, 14 figures

Its neighbourhood

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The 8 papers on this site closest to this one, judged by the topics they share, the words and phrases in their titles and abstracts, and their authors. They are not its citations, but a map of the work around it. Papers here go back to 2021, plus the canon.

Connected papers This paper in the centre and the 8 papers closest to it around it, in date order clockwise from the top. The closer a paper sits to the centre, the stronger the connection. This paper Dynamically Stable Poincaré Embeddings for Neural Manifolds (Jun Chen, Yuang Liu, Xiangrui Zhao et al., 2021)2Chen 2021 Metric Flows with Neural Networks (James Halverson and Fabian Ruehle, 2023)5Halverson 2023 A Ricci flow on graphs from effective resistance (Aleyah Dawkins, Vishal Gupta, Mark Kempton et al., 2024)6Dawkins 2024 Deep Learning as Ricci Flow (Anthony Baptista, Alessandro Barp, Tapabrata Chakraborti et al., 2024)1Baptista 2024 Extensions and Applications of Bredon's Trick in Geometric and Topological Contexts (Mauricio Angel, 2025)4Angel 2025 Core detection via Ricci curvature flows on weighted graphs (Juan Zhao, Jicheng Ma, Yunyan Yang et al., 2025)3Zhao 2025 Ricci Flow on Weighted Digraphs with Balancing Factor (Shuliang Bai, Rui Li, Shuang Liu et al., 2025)7Bai 2025 Evolving edge weights via local entropy flow and cohesion flow on graphs (Juan Zhao, Jicheng Ma, Yunyan Yang et al., 2026)8Zhao 2026
Closer to the centre: more closely connected. Clockwise from the top: oldest to newest. Ricci flowWider flowsalso connected to each other
  1. Deep Learning as Ricci Flow

    Anthony Baptista, Alessandro Barp, Tapabrata Chakraborti et al.

    Topics Discrete & graph Ricci, Weak & singular flows · Shared terms “neural networks”, “geometric transformations”, “activation”

  2. Dynamically Stable Poincaré Embeddings for Neural Manifolds

    Jun Chen, Yuang Liu, Xiangrui Zhao et al.

    Topics Discrete & graph Ricci · Shared terms “neural networks”, “classification tasks”, “Deep neural”

  3. Core detection via Ricci curvature flows on weighted graphs

    Juan Zhao, Jicheng Ma, Yunyan Yang et al.

    Topics Discrete & graph Ricci · Shared terms “community”

  4. Extensions and Applications of Bredon's Trick in Geometric and Topological Contexts

    Mauricio Angel

    Topics Discrete & graph Ricci · Shared terms “neural networks”, “theoretical”

  5. Metric Flows with Neural Networks

    James Halverson and Fabian Ruehle

    Topics Discrete & graph Ricci · Shared terms “neural networks”, “learn feature”, “understanding”

  6. Ricci Flow on Weighted Digraphs with Balancing Factor

    Shuliang Bai, Rui Li, Shuang Liu et al.

    Topics Discrete & graph Ricci · Shared terms “graph representation”, “community”, “Building”

  7. Evolving edge weights via local entropy flow and cohesion flow on graphs

    Juan Zhao, Jicheng Ma, Yunyan Yang et al.

    Topics Discrete & graph Ricci · Shared terms “Empirical”, “community”

Read around it

Background reading

The guides for the topics of this paper: what each idea is, why it matters, and the papers to read first.

In the guidebook

  1. 6D.11
    Computing Geometric FlowsBook 6D · Diffusions, Finance and Computation

    Numerical curve shortening and mean curvature flow, level sets and phase fields, discrete Ricci flow on surfaces and in conformal mapping, rotationally symmetric neckpinches, and what computation has taught about singularities.

  2. 12C.9
    After PerelmanBook 12C · Extinction and the Proof

    Singular flows, the Smale conjecture, and Bamler’s theory.

  3. 5A.5
    Uniformization and the Two-Dimensional Ricci FlowBook 5A · Complex Analysis and Conformal Geometry

    Constant-curvature metrics on surfaces, and Ricci flow as a heat equation for the conformal factor.