Paper · Dec 18, 2024

Non-collapsing of Ricci shrinkers with bounded curvature

Conghan Dong, Yu Li

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Abstract

We establish a uniform entropy bound for simply connected Ricci shrinkers with a finite second homotopy group and a uniform curvature bound. Additionally, we extend the non-collapsing result to a broader class of smooth metric measure spaces satisfying Bakry-Émery conditions.

Comments: 35 pages

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Connected papers

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 Rigidity of the round cylinders in Ricci shrinkers (Yu Li and Bing Wang, 2021)1Li 2021 Rigidity of complex projective spaces in Ricci shrinkers (Yu Li and Wenjia Zhang, 2022)2Li 2022 Heat kernel on Ricci shrinkers (II) (Yu Li and Bing Wang, 2023)5Li 2023 On the rigidity of Ricci shrinkers (Yu Li and Wenjia Zhang, 2023)7Li 2023 On the structure of noncollapsed Ricci flow limit spaces (Hanbing Fang and Yu Li, 2025)3Fang 2025 Singular sets in noncollapsed Ricci flow limit spaces (Hanbing Fang and Yu Li, 2025)8Fang 2025 Gromov-Hausdorff Limits of Noncollapsed Kähler-Ricci Flows and the Geometry of Ricci Shrinkers (Yu Li and Junsheng Zhang, 2026)4Li 2026 On the geometry of asymptotically conical Ricci shrinkers (I): weighted analysis (Yu Li, Longhuan Yan and Wenjia Zhang, 2026)6Li 2026
Closer to the centre: more closely connected. Clockwise from the top: oldest to newest. Ricci flowWider flowsalso connected to each other
  1. Rigidity of the round cylinders in Ricci shrinkers

    Yu Li and Bing Wang PDF

    Topics Limit spaces & RCD, Ricci solitons · Same author Yu Li · Shared terms “Ricci shrinkers”

  2. Rigidity of complex projective spaces in Ricci shrinkers

    Yu Li and Wenjia Zhang PDF

    Topics Limit spaces & RCD, Ricci solitons · Same author Yu Li · Shared terms “Ricci shrinkers”

  3. On the structure of noncollapsed Ricci flow limit spaces

    Hanbing Fang and Yu Li PDF

    Topics (Non)collapsing, Limit spaces & RCD · Same author Yu Li

  4. Gromov-Hausdorff Limits of Noncollapsed Kähler-Ricci Flows and the Geometry of Ricci Shrinkers

    Yu Li and Junsheng Zhang PDF

    Topics (Non)collapsing, Limit spaces & RCD, Ricci solitons · Same author Yu Li · Shared terms “Ricci shrinkers”

  5. Heat kernel on Ricci shrinkers (II)

    Yu Li and Bing Wang PDF

    Topics Limit spaces & RCD, Ricci solitons · Same author Yu Li · Shared terms “Ricci shrinkers”

  6. On the geometry of asymptotically conical Ricci shrinkers (I): weighted analysis

    Yu Li, Longhuan Yan and Wenjia Zhang PDF

    Topics Limit spaces & RCD, Ricci solitons · Same author Yu Li · Shared terms “Ricci shrinkers”

  7. On the rigidity of Ricci shrinkers

    Yu Li and Wenjia Zhang PDF

    Topics Limit spaces & RCD, Ricci solitons · Same author Yu Li · Shared terms “Ricci shrinkers”

  8. Singular sets in noncollapsed Ricci flow limit spaces

    Hanbing Fang and Yu Li PDF

    Topics (Non)collapsing, Limit spaces & RCD · Same author Yu Li · Shared terms “curvature bounds”

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. 9B.3
    Collapsing and NoncollapsingBook 9B · Comparison, Convergence and Heat on Manifolds

    Injectivity radius bounds from volume, collapsing examples, and the definition Perelman needs.

  2. 12A.4
    κ-NoncollapsingBook 12A · Entropy and Noncollapsing

    The theorem that excludes the cigar.

  3. 12A.8
    Local Noncollapsing from the Reduced VolumeBook 12A · Entropy and Noncollapsing

    Perelman's §§7.3 and 8: noncollapsing that needs only local curvature control, the small-and-large-vector split, the maximum principle for the reduced distance, and the form that survives surgery.