Paper · Mar 28, 2024

Four-dimensional gradient Ricci solitons with (half) nonnegative isotropic curvature

Huai-Dong Cao, Junming Xie

math.DGarXiv:2403.19627v3J. Math. Pures Appl. (9) 197 (2025), Paper No. 103686
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Abstract

This is a sequel to our paper [24], in which we investigated the geometry of 4-dimensional gradient shrinking Ricci solitons with half positive (nonnegative) isotropic curvature. In this paper, we mainly focus on 4-dimensional gradient steady Ricci solitons with nonnegative isotropic curvature (WPIC) or half nonnegative isotropic curvature (half WPIC). In particular, for 4D complete ancient solutions with WPIC, we are able to prove the 2-nonnegativity of the Ricci curvature and bound the curvature tensor Rm by |Rm|\leq R. For 4D gradient steady solitons with WPIC, we obtain a classification result. We also give a partial classification of 4D gradient steady Ricci solitons with half WPIC. Moreover, we obtain a preliminary classification result for 4D complete gradient expanding Ricci solitons with WPIC. Finally, motivated by the recent work [59], we improve our earlier results in [24] on 4D gradient shrinking Ricci solitons with half PIC or half WPIC, and also provide a characterization of complete gradient Kaehler-Ricci shrinkers in complex dimension two among 4-dimensional gradient Ricci shrinkers.

Comments: 21 pages; v.3: Corrected Lemma 2.2 and modified Theorem 1.1; removed Corollary 1.3 in version 2

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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 Curvature estimates for four-dimensional complete gradient expanding Ricci solitons (Huai-Dong Cao and Tianbo Liu, 2021)6Cao 2021 Complete gradient expanding Ricci solitons with finite asymptotic scalar curvature ratio (Huai-Dong Cao, Tianbo Liu and Junming Xie, 2022)7Cao 2022 Four-dimensional complete gradient shrinking Ricci solitons with half positive isotropic curvature (Huai-Dong Cao and Junming Xie, 2022)1Cao 2022 On Shrinking Ricci solitons with positive isotropic curvature in higher dimensions (Zhengnan Chen, 2025)5Chen 2025 Curvature pinching of asymptotically conical gradient expanding Ricci solitons (Huai-Dong Cao and Junming Xie, 2025)3Cao 2025 On curvature estimates for four-dimensional gradient Ricci solitons (Huai-Dong Cao, 2025)4Cao 2025 A note on the classification of four-dimensional gradient steady and expanding Ricci solitons (Huai-Dong Cao and Junming Xie, 2026)2Cao 2026 O(3)-symmetry of four-dimensional steady Ricci solitons (Hanbing Fang, 2026)8Fang 2026
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  1. Four-dimensional complete gradient shrinking Ricci solitons with half positive isotropic curvature

    Huai-Dong Cao and Junming Xie PDF

    Topics Sphere theorems, 4-manifolds, Kähler geometry · Same authors Huai-Dong Cao, Junming Xie · Shared terms “nonnegative isotropic”, “isotropic curvature”, “half positive”

  2. A note on the classification of four-dimensional gradient steady and expanding Ricci solitons

    Huai-Dong Cao and Junming Xie PDF

    Topics 4-manifolds, Ricci solitons · Same authors Huai-Dong Cao, Junming Xie · Shared terms “dimensional gradient”, “gradient steady”, “nonnegative isotropic”

  3. Curvature pinching of asymptotically conical gradient expanding Ricci solitons

    Huai-Dong Cao and Junming Xie PDF

    Topics Sphere theorems, 4-manifolds, Ancient solutions · Same authors Huai-Dong Cao, Junming Xie · Shared terms “dimensional gradient”, “isotropic curvature”, “gradient expanding”

  4. On curvature estimates for four-dimensional gradient Ricci solitons

    Huai-Dong Cao PDF

    Topics 4-manifolds, Ricci solitons · Same author Huai-Dong Cao · Shared terms “dimensional gradient”, “gradient steady”, “steady Ricci”

  5. On Shrinking Ricci solitons with positive isotropic curvature in higher dimensions

    Zhengnan Chen PDF

    Topics Sphere theorems, 4-manifolds, Ancient solutions · Shared terms “isotropic curvature”, “WPIC”, “shrinking Ricci”

  6. Curvature estimates for four-dimensional complete gradient expanding Ricci solitons

    Huai-Dong Cao and Tianbo Liu PDF

    Topics 4-manifolds, Ricci solitons · Same author Huai-Dong Cao · Shared terms “complete gradient”, “gradient expanding”, “four dimensional”

  7. Complete gradient expanding Ricci solitons with finite asymptotic scalar curvature ratio

    Huai-Dong Cao, Tianbo Liu and Junming Xie PDF

    Topics Ricci solitons · Same authors Huai-Dong Cao, Junming Xie · Shared terms “complete gradient”, “gradient expanding”, “expanding Ricci”

  8. -symmetry of four-dimensional steady Ricci solitons

    Hanbing Fang PDF

    Topics Sphere theorems, 4-manifolds, Ricci solitons · Shared terms “steady Ricci”, “dimensional gradient”, “four dimensional”

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Background reading

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In the guidebook

  1. 12B.2
    The Asymptotic Soliton and Three-Dimensional ShrinkersBook 12B · κ-Solutions and Surgery

    Perelman's Proposition 11.2 proved with Morgan and Tian: the reduced-length bounds on κ-solutions, the limit of rescalings, the equality case, and the classification of shrinking solitons in dimensions two and three.

  2. 11A.11
    Hamilton’s 1982 TheoremBook 11A · The Ricci Flow: Existence and Maximum Principles

    Positive Ricci curvature in dimension 3 flows to a round metric.

  3. 11B.2
    Ancient Solutions and the Harnack InequalityBook 11B · Solitons, Compactness and Singularities

    Comparing curvature across space and time.