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Type-II smoothing in mean curvature flow

Sigurd Angenent, Panagiota Daskalopoulos and Nataša Šešum

Vol. 19 (2026), No. 5, 857–908
Abstract

Velázquez (1994) constructed a smooth O(4) × O(4) invariant mean curvature flow that forms a type-II singularity at the origin in spacetime. Stolarski (2023) showed that the mean curvature on this solution is uniformly bounded. In a work in preparation, Angenent, Ilmanen, and Velázquez (Angenent et al.) also provided formal asymptotic expansions for a possible smooth continuation of the solution after the singularity.

Here we prove short-time existence of Velázquez’ formal continuation, and we verify that the mean curvature is also uniformly bounded on the continuation. Combined with the earlier results of Velázquez and Stolarski we therefore show that there exists a solution {Mt7 8 t0 < t < t0} that has an isolated singularity at the origin 0 8 and at t = 0; moreover, the mean curvature is uniformly bounded on this solution, even though the second fundamental form is unbounded near the singularity.

Keywords
mean curvature flow, singularity with bounded mean curvature
Mathematical Subject Classification
Primary: 53E10
Milestones
Received: 7 June 2023
Revised: 18 December 2024
Accepted: 27 August 2025
Published: 21 May 2026
Authors
Sigurd Angenent
Department of Mathematics
University of Wisconsin–Madison
Madison, WI
United States
Panagiota Daskalopoulos
Department of Mathematics
Columbia University
New York, NY
United States
Nataša Šešum
Department of Mathematics
Rutgers University
Piscataway, NJ
United States

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