Organizers: Raphael Tsiamis, Yipeng Wang
Time: Mondays 4:30 - 6:30 pm
Location: Columbia Math Department, Room 507
This seminar will survey recent developments in the analysis of singularities in mean curvature flow, with an emphasis on flows that are locally modeled on cylinders ("asymptotically cylindrical"). We will begin by reviewing the modern “weak-solution” viewpoint (Brakke/level-set formulations), blow-up and tangent-flow analysis, and the role of cylindrical models in the structure theory near generic singularities. The main focus of the seminar will be the recent Bamler-Lai proof of the Mean Convex Neighborhood Conjecture: roughly, whenever a singular point has a multiplicity-one cylindrical tangent flow, the ambient flow is forced to become mean-convex in a neighborhood of that point and admits a canonical-neighborhood description by explicit local models.
We will then see how these ideas feed into a classification of ancient asymptotically cylindrical flows—showing that such solutions fall into a small number of canonical families (ancient ovals, bowl-type translators, and flying-wing translators)—and how this classification underpins the proof of the mean-convex neighborhood and canonical-neighborhood theorems.
Time permitting, we will discuss related progress on the Multiplicity One Conjecture (notably for the flow of surfaces in ℝ3) and consequences for well-posedness and fattening/ nonfattening phenomena. We will also cover recent advances in the classification program for ancient noncollapsed flows and translators in ℝ4, including bubble-sheet ovals and analytic foundations for the linearized translator equation.
Primary readings will be drawn from: arXiv:2512.24524, 2512.25050, 2312.02106, 2509.07629, 2509.06667, 2412.10581, 2305.19137, 2209.04931.
Bamler, R., Lai, Y., Classification of ancient cylindrical mean curvature flows and the Mean Convex Neighborhood Conjecture. Preprint arXiv:2512.24524 (2025)
Bamler, R. H., Lai, Y., The PDE-ODI principle and cylindrical mean curvature flows. Preprint arXiv:2512.25050 (2025).
Bamler, R. H., Kleiner, B., On the Multiplicity One Conjecture for Mean Curvature Flows of Surfaces. Preprint arXiv:2312.02106 (2023)
Choi, B., Daskalopoulos, P., Du, W., Haslhofer, R., Sesum, N., Classification of bubble-sheet ovals in ℝ4. Geom. Topol. 29, 931-1016 (2025) URL
Choi, K., Haslhofer, R., Classification of ancient noncollapsed flows in ℝ4. Preprint arXiv:2412.10581 (2024).
Choi, K., Haslhofer, R., Hershkovits, O., Ancient low-entropy flows, mean-convex neighborhoods, and uniqueness. Acta Math. 228, 217–301 (2022) URL
Choi, K., Haslhofer, R., Hershkovits, O., A gradient estimate for the linearized translator equation. Preprint arXiv:2509.07629 (2025).
Choi, K., Haslhofer, R., Hershkovits, O., The linearized translator equation and applications. Preprint arXiv:2509.06667 (2025).
Choi, K., Haslhofer, R., Hershkovits, O., Enhanced profile estimates for ovals and translators. Adv. Math. 453, Art. 109853 (2024) URL
Choi, K., Haslhofer, R., Hershkovits, O., A non-existence result for wing-like mean curvature flows in ℝ4. Geom. Topol. 28 (7), 3095-3134 (2024) URL
Choi, K., Haslhofer, R., Hershkovits, O., White, B., Ancient asymptotically cylindrical flows and applications. Invent. Math. 229, 139-241 (2022)
In the first meeting, we will set out the goals of the seminar and discuss various aspects of the references, schedule, and content of the talks.