Paper · Aug 31, 2026

Ancient cylindrical flows with fast or slow convergence

Kyeongsu Choi, Robert Haslhofer

math.DGWider flowsarXiv:2608.30787
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Abstract

In a recent breakthrough, Bamler-Lai proved the mean-convex neighborhood conjecture in all dimensions by showing that any nontrivial ancient asymptotically cylindrical mean curvature flow is – up to splitting Euclidean factors – either a translating bowl, or an ancient oval, or a translating oval-bowl. In this paper, we provide a short alternative argument for two of the three scenarios. Specifically, using more elementary/traditional methods, we show that if the convergence to the round cylinder is fast then the solution is a bowl times a Euclidean factor, and if the convergence is slow then the solution is an ancient oval. Moreover, the present paper also yields a new proof of the mean-convex neighborhood conjecture for neck-singularities that substantially simplifies and streamlines the approach from our prior work joint with Hershkovits (Acta '22) and Hershkovits-White (Inventiones '22).

Comments: 13 pages

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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 Hearing the shape of ancient noncollapsed flows in ℝ⁴ (Wenkui Du and Robert Haslhofer, 2021)6Du 2021 Classification of bubble-sheet ovals in ℝ⁴ (Beomjun Choi, Panagiota Daskalopoulos, Wenkui Du et al., 2022)8Choi 2022 Enhanced profile estimates for ovals and translators (Kyeongsu Choi, Robert Haslhofer and Or Hershkovits, 2023)4Choi 2023 Revisiting generic mean curvature flow in ℝ³ (Otis Chodosh, Kyeongsu Choi, Christos Mantoulidis et al., 2024)5Chodosh 2024 Classification of ancient noncollapsed flows in ℝ⁴ (Kyeongsu Choi and Robert Haslhofer, 2024)1Choi 2024 Classification of ancient cylindrical mean curvature flows and the Mean Convex Neighborhood Conjecture (Richard H. Bamler and Yi Lai, 2025)3Bamler 2025 Classification of ancient ovals in higher dimensional mean curvature flow (Beomjun Choi, Wenkui Du and Ziyi Zhao, 2026)7Choi 2026 Free boundary flow through cylindrical singularities (Yueheng Bao and Robert Haslhofer, 2026)2Bao 2026
Closer to the centre: more closely connected. Clockwise from the top: oldest to newest. Ricci flowWider flowsalso connected to each other
  1. Classification of ancient noncollapsed flows in

    Kyeongsu Choi and Robert HaslhoferWider flows PDF

    Topics Ancient solutions, Singularities · Same authors Kyeongsu Choi, Robert Haslhofer · Shared terms “Hershkovits”, “White”, “Specifically”

  2. Free boundary flow through cylindrical singularities

    Yueheng Bao and Robert HaslhoferWider flows PDF

    Topics Ancient solutions, Singularities · Same author Robert Haslhofer · Shared terms “convex neighborhood”, “cylindrical flows”, “Bamler Lai”

  3. Classification of ancient cylindrical mean curvature flows and the Mean Convex Neighborhood Conjecture

    Richard H. Bamler and Yi LaiWider flows PDF

    Topics Ancient solutions, Singularities · Shared terms “ancient cylindrical”, “neighborhood conjecture”, “convex neighborhood”

  4. Enhanced profile estimates for ovals and translators

    Kyeongsu Choi, Robert Haslhofer and Or Hershkovits PDF

    Topics Ancient solutions · Same authors Kyeongsu Choi, Robert Haslhofer · Shared terms “ancient ovals”

  5. Revisiting generic mean curvature flow in

    Otis Chodosh, Kyeongsu Choi, Christos Mantoulidis et al.Wider flows PDF

    Topics Ancient solutions, Singularities · Same author Kyeongsu Choi · Shared terms “Bamler”

  6. Hearing the shape of ancient noncollapsed flows in

    Wenkui Du and Robert HaslhoferWider flows PDF

    Topics Ancient solutions, Singularities · Same author Robert Haslhofer · Shared terms “Hershkovits”, “oval bowl”, “ancient ovals”

  7. Classification of ancient ovals in higher dimensional mean curvature flow

    Beomjun Choi, Wenkui Du and Ziyi ZhaoWider flows PDF

    Topics Ancient solutions · Shared terms “ancient ovals”, “Bamler Lai”, “neighborhood conjecture”

  8. Classification of bubble-sheet ovals in

    Beomjun Choi, Panagiota Daskalopoulos, Wenkui Du et al.Wider flows PDF

    Topics Ancient solutions · Same author Robert Haslhofer · Shared terms “ancient ovals”, “Hershkovits”

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. 12B.3
    The Structure of κ-SolutionsBook 12B · κ-Solutions and Surgery

    Necks and caps, compactness, and universal estimates.

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

    Comparing curvature across space and time.

  3. 12B.1
    κ-SolutionsBook 12B · κ-Solutions and Surgery

    Ancient, nonnegatively curved, noncollapsed: the models for singularities.