Paper · Oct 2, 2026

On the uniqueness of Ricci flows from certain Alexandrov spaces

Laura Flower

As on arXiv

Abstract

We consider the problem of uniqueness of Ricci flows, starting from singular initial data. Even when the initial data is smooth and smoothly obtained, in the complete noncompact case uniqueness is not known in full generality. When starting from nonsmooth initial data, very little is known, even in the compact case. We obtain a uniqueness result for Ricci flows with scaling-invariant curvature bounds, a suitable noncollapsing assumption, and sectional curvature lower bounds, coming out of (possibly singular) Reifenberg spaces. As a consequence of our result, and existence results obtained by Simon–Topping and Lai, there is a canonical way to define a smooth structure on any Reifenberg uniformly volume-noncollapsed PIC2 limit space. Further, we obtain a diffeomorphic version of Perelman's stability theorem for these limit spaces.

Submitted
Oct 2, 2026
Subjects
math.DG

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  1. The Singular Fibration of Collapsing RCD Spaces with Reifenberg Local Covers

    Shaosai Huang

    Topics (Non)collapsing, Weak & singular flows, Boundaries & non-compact · Shared terms “Reifenberg”

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    Topics (Non)collapsing, Boundaries & non-compact, Stability & uniqueness · Shared terms “scaling invariant”, “invariant curvature”, “curvature bounds”

  3. Preserving curvature lower bounds when Ricci flowing non-smooth initial data

    Miles Simon

    Topics Weak & singular flows · Shared terms “initial data”, “curvature lower”, “lower bound”

  4. On the Hamilton-Lott conjecture in higher dimensions

    Alix Deruelle, Felix Schulze and Miles Simon

    Topics (Non)collapsing, Weak & singular flows, Boundaries & non-compact · Shared terms “Reifenberg”, “PIC”

  5. On an invariant curvature cone along 4-dimensional Ricci flow

    Hongting Ding, Shaochuang Huang and Zhuo Peng

    Topics (Non)collapsing, Boundaries & non-compact · Shared terms “invariant curvature”, “curvature lower”, “complete noncompact”

  6. Pseudolocality and completeness for nonnegative Ricci curvature limits of 3D singular Ricci flows

    Albert Chau and Adam Martens

    Topics Weak & singular flows, Boundaries & non-compact · Shared terms “Lai”, “sectional curvature”, “complete noncompact”

  7. Rotationally symmetric Ricci Flow on

    Ming Hsiao

    Topics (Non)collapsing, Weak & singular flows · Shared terms “scaling invariant”, “invariant curvature”, “curvature bounds”

  8. On the structure of noncollapsed Ricci flow limit spaces

    Hanbing Fang and Yu Li

    Topics (Non)collapsing · Shared terms “limit space”, “noncollapsed”

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.