(O): Regular talks of the Oberseminar (For internal talks, see the webpage of our Research Seminar.)
(S): Talks that additionally are part of the "Seminar on Differential Geometry and Analysis", coorganized by HansChristoph Grunau, Miles Simon (OttovonGuericke Universität Magdeburg) and Roger Bielawski, Knut Smoczyk (Leibniz Universität Hannover).
All talks in Summer 2024 take place at LUH in Raum B302: Klaus Fröhlich Hörsaal, Hauptgebäude (Welfengarten 1), except those talks marked (M).
(M): Meetings that take place in Magdeburg.
For any questions regarding the information on this webpage please contact Nikolas Eptaminitakis.
Summer semester 2024
18.04.2024 (O)  15:0016:00  Prof. Dr. Guofang Wang (Universität Freiburg)  Title: Capillary hypersurfaces: Geometric inequalities, flows and related problems Abstract: In this talk, we first introduce geometric quantities for capillary hypersurfaces, and then establish isoperimetric type inequalities, AlexandrovFenchel inequalities, by studying corresponding geometric flows. We will also talk about a related Minkowski type problem and other related problems. The talk is based on a joint work with Chao Xia and other collaborators. 
18.04.2024 (O)  16:3017:30  Prof. Dr. KarlTheodor Sturm (Universität Bonn)  Title: Metric Measure Spaces and Synthetic Ricci Bounds Abstract: Metric measure spaces with synthetic Ricci bounds have attracted great interest in recent years, accompanied by spectacular breakthroughs and deep new insights. The talk will provide a brief introduction to the concept of uniform lower Ricci bounds as introduced by Lott–Villani and myself, and illustrate some of its geometric, analytic, and probabilistic consequences.

25.04.2024 (M)  15:0016:00  Dr. PakYeung Chan (UC San Diego/Warwick University)  Title: Gap theorem for nonnegatively curved manifolds Abstract: In this seminar, we shall discuss some recent results on the gap theorem of nonnegatively curved manifolds with small curvature in an average integral sense, which can be viewed as a Riemannian analogue of the optimal gap result by Ni on Kaehler manifolds. In dimension 3, we also establish a gap theorem for Ricci nonnegative manifolds with pointwise quadratic curvature decay and fast average integral curvature decay. This talk is based on some joint works with ManChun Lee. 
25.04.2024 (M)  16:3017:30  Dr. Huy Nguyen (Queen Mary University of London)  Title: Mean Curvature Flow in the Sphere Abstract: In this talk, I will discuss some recent results analysing singularities of the mean curvature flow in the sphere both in the hypersurface case and the high codimension case. 
06.06.2024 (O)  15:0016:00  Dr. Riccardo Tione (MPI Leipzig)  Title: On the LawsonOsserman conjecture Abstract: In 1977, H.B. Lawson and R. Osserman conjectured that Lipschitz maps which are critical with respect to outer variations of the area functional are also critical with respect to domain variations. In this talk I will present a solution to this conjecture in the planar case. This result was obtained in collaboration with J. Hirsch and C. Mooney. 
06.06.2024 (O)  16:3017:30  Prof. Dr. Christian Bär (Universität Potsdam)  Title: A holographic index theorem and applications to scalar curvature geometry Abstract: In the first part of the talk I will discuss a "holographic" index theorem for compact manifolds with boundary. It relates the index of a boundary value problem to the index of an operator on the boundary. It will then be applied to scalar curvature geometry. We will show a ridigidity theorem for scalar curvature on certain warped product spaces. This implies, in particular, Llarull's theorem for the punctured sphere, as conjectured by Gromov. 
04.07.2024 (S)  15:0016:00  Prof. Dr. Luciano Mari (University of Milan)  Title: Prescribing the Lorentzian mean curvature of a spacelike hypersurface, and the BornInfeld model Abstract: The talk aims to introduce the reader to the existence and regularity problem for spacelike hypersurfaces in LorentzMinkowski space whose mean curvature is a prescribed measure. The class includes, for instance, maximal surfaces with point singularities. Motivation comes from General Relativity and from the electrostatic BornInfeld theory, according to which the graph function represents the electric potential and its mean curvature the given charge distribution. Various open problems will be discussed. The talk is based on joint works with J. Byeon, N. Ikoma, A. Malchiodi and L. Maniscalco. 
04.07.2024 (S)  16:3017:30  Prof. Dr. Boris Vertman (Universität Oldenburg)  Title: Microlocal Analysis on manifolds with fibered boundaries Abstract: We discuss spectral geometric questions on on some noncompact manifolds with fibered boundaries. Main examples include noncompact complete hyperKähler 4manifolds and scattering spaces. We discuss how such spaces naturally arise in the analysis of analytic torsion under degeneration of a smooth compact manifold to a space with conical singularities. This is a recent project with Jørgen Olsen Lye. 
Winter semester 2023/2024
16.11.2023 (O)  15 Uhr (s.t.)  Prof. Dr. Benoit Charbonneau (University of Waterloo)  Title: Symmetric Instantons 
06.12.2023 Unusual Day and Location: Welfengarten 1 (Hauptgebäude), G005  17:0018:00  Prof. Dr. Niels Martin Møller (University of Copenhagen)  Title: Rigidity of the grim reaper cylinder as a collapsed selftranslating soliton Abstract: Mean curvature flow selftranslating solitons are minimal hypersurfaces for a certain incomplete conformal background metric, and are among the possible singularity models for the flow. In the collapsed case, they are confined to slabs in space. The simplest nontrivial such example, the grim reaper curve $\Gamma$ in $\mathbb{R}^2$, has been known since 1956, as an explicit ODEsolution, which also easily gave its uniqueness. We consider here the case of surfaces, where the rigidity result for $\Gamma\times\mathbb{R}$ that we'll show is: The grim reaper cylinder is the unique (up to rigid motions) finite entropy unit speed selftranslating surface which has width equal to $\pi$ and is bounded from below. (Joint with Impera & Rimoldi.) Time permitting, we'll also discuss recent uniqueness results in the collapsed simplyconnected low entropy case (w/ E.S. Gama & F. Martín), using Morse theory and nodal set techniques, which extend Chini's classification. 
07.12.2023 (S)  16:3017:30  Dr. Enno Keßler (MaxPlanckInstitut für Mathematik in den Naturwissenschaften Leipzig)  Title: Super Jholomorphic curves Abstract: Jholomorphic curves or pseudoholomorphic curves are maps from Riemann 
07.12.2023 (S)  15:0016:00  Prof. Dr. Francisco Martin (University of Granada)  Title: Semigraphical Translators of the Mean Curvature Flow Abstract: A soliton is a special solution to a partial differential equation that maintains its shape and moves at a constant velocity. In the context of mean curvature flow, a translating soliton is a solution to the mean curvature flow equation that moves by a constant velocity in the direction of a vector. Translating solitons are particularly interesting because they provide insights into the behavior of evolving surfaces. On the other hand, we say that a surface is semigraphical if when we remove a discrete set of vertical lines, then the resulting surface is the graph of a smooth function. We are going to provide a classification of all the semigraphical translator in Euclidean 3space. First, we will describe a comprehensive zoo of all examples of this type of translators, and then we will focus on classification arguments. We will conclude with some open problems. This talk summarizes various joint works with D. Hoffman and B. White, on one hand, and with M. Saez and R. Tsiamis, on the other. 
18.01.2024  16:3017:30  Prof. Dr. HansJoachim Hein (Universität Münster)  Title: A gluing construction for complex surfaces with hyperbolic cusps Abstract: We will describe an example of a degeneration of degree 6 algebraic surfaces in CP^3 with only ordinary triple point singularities on its central fiber. Then we will show how the unique negative KählerEinstein metrics on the smooth fibers, which exist by the AubinYau theorem, disintegrate into three distinct geometric pieces on approach to the central fiber: (1) Kobayashi's complete KählerEinstein metric on the complement of the triple points, (2) long thin neck regions, and (3) TianYau's complete Ricciflat Kähler metrics in small neighborhoods of the vanishing cycles. Joint work with Xin Fu and Xumin Jiang. 
18.01.2024  15:0016:00  Prof. Dr. Jason D. Lotay (University of Oxford)  Title: Translators in Lagrangian mean curvature flow Abstract: Lagrangian mean curvature flow is potentially a powerful tool in solving problems in symplectic topology. One of the key challenges is the understanding of formation of singularities, which is conjectured to have links to Jholomorphic curves, stability conditions and the Fukaya category. Unlike the usual mean curvature flow for hypersurfaces, here one is expected to have to tackle singularities modelled on translating solutions to the flow. I will describe joint work with Felix Schulze and Gabor Szekelyhidi which allows one to recognize a singularity model in Lagrangian mean curvature flow as a translator  this is the first such result in any form of mean curvature flow beyond curves. 
Sommer semester 2023
13.07.2023 (B302)  16:3017:30  Prof. Dr. Ernst Kuwert (Freiburg)  Title: Curvature varifolds with orthogonal boundary. Abstract: We consider surfaces in a domain with orthogonal boundary condition. The problem to obtain mass bounds in terms of curvature bounds leads to a varifold setting (joint work with Marius Mueller). 
13.07.2023 (B302)  15:0016:00  Prof. Dr. Oliver Schnürer (Konstanz  Title: Unbounded solutions to mean curvature flow Abstract:We discuss several aspects of complete noncompact solutions to graphical mean curvature flow in Euclidean space in codimension one: 
27.04.2023 (B302)  15:0017:30  Special guests on Research Seminar  Please attempt to our special guests in the Research Seminar page! 
Winter semester 2022 / 2023
26.01.2023 (S)  16:1517:15  Prof. Tobias Lamm (KIT Karlsruhe)  Title: Index estimates for sequences of harmonic maps Abstract: We study the limiting behavior of the index and the nullity of sequences of harmonic maps from a twodimensional Riemann surface into a general target manifold. We show upper and lower bounds for the index of the sequence in terms of the index of the so called bubble limit. This is a joint work with Jonas Hirsch (Leipzig). 
26.01.2023 (S)  15:0016:00  Dr. Athanasios Chatzikaleas (Uni Münster)  Title: Nonlinear periodic waves in the Antide Sitter spacetime and islands of stability. Abstract: In 2006, DafermosHolzegel conjectured that the Antide Sitter spacetime is an unstable solution to the Einstein equations under reflective boundary conditions for general initial data. RostworowskiMaliborski enhanced this conjecture by proving numerical evidence that indicate the existence of "special" initial data leading to timeperiodic solutions for the EinsteinKleinGordon system which are in fact stable. Motivated by these, we construct families of arbitrary small timeperiodic solutions to several toy models on the fixed Antide Sitter background providing a rigorous proof of the numerical constructions above in a simpler setting. The models we consider include the conformal cubic wave equation and the sphericallysymmetric YangMills equations on the fixed Antide Sitter spacetime and our proof relies on the modifications of a theorem of BambursiPaleari for which the main assumption is the existence of a seed solution, given by a nondegenerate zero of a nonlinear operator associated with the resonant system. 
24.11.2022  15:3016:30  Prof. Umberto Hryniewicz (RWTH Aachen)  Title: A PoincaréBirkhoff Theorem for 3Dimensional Energy Levels Abstract: In subcritical energy levels of the planar circular restricted 3body problem (PCR3BP) Poincaré encountered special periodic orbits that span an annular global section for the flow. This motivated the formulation of what is known today as the PoincaréBirkhoff theorem, from where Poincaré derived beautiful applications to the PCR3BP. In this talk I would like to explain how the action functional from classical mechanics can be used to prove analogous statements for more general systems. This is based on joint work with Al Momin and Pedro Salomão (NYUShanghai). 
24.11.2022 (O)  14:1515:15  Prof. Alberto Abbondandolo (Universität Bochum)  Systolic inequalities in Metric Symplectic Geometry Abstract: The prototypical question of metric systolic geometry is to give upper bounds on the length of the shortest closed geodesics on a closed Riemannian manifold in terms of its volume. Systolic questions have a natural generalization to conservative dynamical systems, in which closed geodesics are replaced by periodic orbits, length by period and volume by phase space volume. This generalization turns out to be quite fruitful: on the one hand, symplectic methods allow us to solve some long standing questions in metric systolic geometry, on the other hand many interesting new questions arise. These new questions are related to challenging open problems in symplectic and in convex geometry. This talk is based on joint works with Gabriele Benedetti, Barney Bramham, Umberto Hryniewicz and Pedro Salomão. 
03.11.2022 (M)  16:0017:00  Prof. Patrick Dondl (Universität Freiburg)  Phase field models with connectedness constrains

03.11.2022 (M)  15:0016:00  Prof. Klaus Kröncke (KTH Stockholm )  Local and Global Scalar curvature rigidity of Einstein Manifolds

Summer semester 2022
28.04.2022 (O)  14:1515:15  Elena MäderBaumdicker (Darmstadt)  Compactification of Minimal flowers and their Morse Index 
05.05.2022 (O)  14:1515:15  Christian Rose (Potsdam)  Compact manifolds with Katobounded Ricci curvature 
19.05.2022 (O)  14:1515:15  Mario Schulz (Münster)  Free boundary minimal surfaces in the unit ball 
Winter semester 2021 / 2022
14.10.2021 (O)  14:1515:15  Hartmut Weiß (Kiel)  Parabolic Higgs bundles and gravitational instantons 
11.11.2021 (O)  14:1515:15  Gianmichele di Matteo (KIT)  Double bubbles with high constant mean curvature in closed manifolds 
25.11.2021 (O)  14:1515:15  Leandro Pessoa (Bielefeld)  Stochastic halfspace theorems for minimal surfaces of R³ and 1surfaces of H³ 
09.12.2021 (O)  14:1515:15  Andreas SavasHalilaj (University of Ioannina)  Graphical mean curvature flow in codimension 2 
Winter semester 2019 / 2020
28.11.2019 (M,S)  15:0016:00  Massimiliano Morini (Parma)  Nonlinear stability results for nonlocal gradient flows (txtDatei) 
28.11.2019 (M,S)  16:3017:30  Ovidiu Munteanu (Storrs, Connecticut)  Green's function estimates and the Poisson equation (txtDatei) 
12.12.2019 (O)  15:0016:00  Jonas Hirsch (Universität Leipzig)  Nonclassical minimizing surfaces with smooth boundary 
12.12.2019 (O)  16:3017:30  Vladimir Matveev (Universität Jena)  Nijenhuis Geometry: singularities and global issues 
30.01.2020 (S)  15:0016:00  Gilles Carron (Université de Nantes)  Volume growth estimates on complete Riemannian manifolds 
30.01.2020 (S)  16:3017:30  Carla Cederbaum (Universität Tübingen)  On CMCfoliations of asymptotically flat manifolds 
Summer semester 2019
09.05.2019 (M,S)  15:0016:00  Matteo Novaga (Università di Pisa)  Anisotropic and crystalline mean curvature flow 
09.05.2019  16:3017:30  Alix Deruelle (Sorbonne Université Paris)  Classification of asymptotically conical 2D shrinking gradient KählerRicci solitons 
06.06.2019  15:0016:00  Karin Melnick (University of Maryland)  A D'Ambra Theorem in conformal Lorentzian geometry 
06.06.2019  16:3017:30  Volker Branding (Universität Wien)  Higher order generalizations of harmonic maps 
04.07.2019 (S)  15:0016:00  Tobias Weth (GoetheUniversität Frankfurt)  Critical domains for the first nonzero Neumann eigenvalue in Riemannian manifolds 
04.07.2019 (S)  16:3017:30  Boris Vertman (Carl von Ossietzky Universität Oldenburg)  Perelman Entropies on Singular spaces 