For the 2025 summer semester, the seminar meets on Mondays, 13:15-14:45 in room 2.006 at the HU math department (Rudower Chaussee 25). See below for a precise schedule.
New feature this semester: There will be coffee and cookies after the seminar!
If you plan to participate in the seminar, please join the moodle (the enrollment key is "cookies"). The moodle will be used for occasional time-sensitive announcements. Users affiliated with the HU can access moodle using their HU username and password. Non-HU users can access it by following this link and then clicking on "Create new account".
The seminar will begin in the fourth week of the semester.
| Monday April 14, 2025 | No seminar |
|---|---|
| Monday April 21, 2025 | No seminar due to the Easter holiday |
| Monday April 28, 2025 | No seminar due to the knot theory workshop in Potsdam |
| Monday May 5, 2025 13:15-14:45 RUD 25, Room 2.006 |
Speaker: Gerard Bargallo Topic: Fuk, fragile symmetries Abstract: In his thesis, Seidel studied symmetries of symplectic manifolds that are "fragile" (with respect to the symplectic form) to explain instances of non-trivial symplectic phenomena that are however smoothly invisible. For example, this ultimately explains why Lagrangian spheres can be smoothly unknotted but symplectically knotted. My aim in this talk is to explain why Floer theory (which I will introduce) is the right tool to deal with these kinds of problems. We will extrapolate basic features of Floer (co)homology in this context to features of the Fukaya category, which is one of the central invariants of symplectic manifolds and one of the two key parts of homological mirror symmetry, for example. If time permits (i.e. if I managed to understand all the above well enough to give succinct explanations) I may quickly explain how to compute Floer homology of cleanly intersecting Lagrangians (cute and geometric spectral sequence argument). |
| Friday May 9, 2025 13:30-15:00 RUD 25, Room 1.023 (BMS Seminar Room) |
Speaker: Agustin Moreno (Heidelberg) Topic: Exotic contact structures on the sphere and beyond Abstract: By work of Eliashberg in dimension 3 and Borman-Eliashberg-Murphy in higher dimensions, there are two flavors of contact structures: tight (geometric/rigid), and overtwisted (topological/flexible). Tight contact structures are much harder to classify than the overtwisted ones (which satisfy an h-principle, and so are abundant). One way to understand tight structures is via their symplectic fillings. In this talk, I will explain how in dimension at least 5, the odd-dimensional sphere admits contact structures which are exotic from a symplectic point of view, namely they are tight but admit no (strong) symplectic filling. This is in stark contrast to the three-dimensional case, as Eliashberg showed there is a unique tight contact structure on the 3-sphere (which is fillable). Time permitting, I will discuss applications to arbitrary topology, and to different flavors of fillability. This is based on joint work with Jonathan Bowden, Fabio Gironella and Zhengyi Zhou. |
| Monday May 12, 2025 | No seminar due to special talk on Friday 9.05 instead |
| Monday May 19, 2025 13:15-14:45 RUD 25, Room 2.006 |
Speaker: Julio Sampietro Christ (Paris-Saclay) Topic: Equivariant Lagrangian Floer homology and the Cartan isomorphism Abstract: In this talk we’ll go from classical equivariant homology to equivariant Lagrangian Floer homology, making stops at various places such as the land of quilts. Then we will prove the Floer version of the Cartan isomorphism and, if time permits, give some applications. |
| Monday May 26, 2025 13:15-14:45 RUD 25, Room 2.006 |
Speaker: Jacek Rzemieniecki Topic: Locality in the Fukaya category of a hyperkähler manifold |
| Monday June 2, 2025 13:15-14:45 RUD 25, Room 2.006 |
Speaker: David Suchodoll Topic: Multiplicity of knot floer order |
| Monday June 9, 2025 | No seminar due to the Pentecost holiday |
| Wednesday June 11, 2025 16:30-18:00 RUD 25, Room 1.013 |
Speaker: Kenny Blakey (MIT) Topic: Bounding Lagrangian intersections via Floer homotopy theory Abstract: In this talk, I will describe applications of Floer homotopy theory to the problem of bounding (possibly degenerate) Lagrangian intersections. |
| Monday June 16, 2025 13:15-14:45 RUD 25, Room 2.006 |
Speakers: Vincent Woltmann and Florian Kaufmann Topic: The Rectangular Peg Problem Abstract: The square peg problem asks the seemingly simple question of whether one can inscribe the vertices of a square into an arbitrary Jordan curve. While this is still unsolved, varying smoothness assumptions have since been developed to give an affirmative answer. The rectangular peg problem now asks what other aspect ratios are allowed for inscribed rectangles. After a short introduction we will use the first half of our talk to present the ideas of Greene & Lobb reducing this in the smooth case to the non-existence of a Lagrangian Klein Bottle in R4. In the second half we will then discuss why R4 admits no Lagrangian Klein Bottle following the ideas of Nemirovski. |
| Monday June 23, 2025 13:15-14:45 RUD 25, Room 2.006 |
Speaker: Apratim Choudhury Topic: Extending Wendl's stratification to compactified Gromov-Witten moduli spaces Abstract: This talk is essentially about deformation theory, in the context of symplectic Gromov-Witten theory. In the first half, we will review how symplectic geometers deal with deformation theory, the main problematic situations which they face in proving transversality, and a very nice resolution by Wendl to handle those situations. The result rests on a technical stratification theorem, whose ideas will be summarized in the talk. In the second half, we will talk about an ongoing work on extending this stratification to compactified moduli spaces, i.e. for nodal holomorphic curves. Time permitting, we will talk about some potential applications of this extension, which is work in progress. |
| Monday June 30, 2025 13:15-14:45 RUD 25, Room 2.006 |
Speaker: Amanda Hirschi (Sorbonne) Topic: Global Kuranishi charts in symplectic Gromov-Witten theory, part 1 Abstract: In this first of two talks, I will give an introduction to the notion of a global Kuranishi chart and what it means for two of them to be equivalent. Subsequently, I will describe the construction of such a chart for moduli spaces of stable pseudo-holomorphic maps in a closed symplectic manifold. The aim is to give details but explain in each case why we do what we do. In the second talk (July 2), I will describe applications of this technology, with the aim to showcase how global Kuranishi charts can be used in practice. The first part is joint work with Mohan Swaminathan. |
| Wednesday July 2, 2025 16:30-18:00 RUD 25, Room 1.013 |
Speaker: Amanda Hirschi (Sorbonne) Topic: Global Kuranishi charts in symplectic Gromov-Witten theory, part 2 (continued from June 30) |
| Friday July 4, 2025 | Berlin-Hamburg Symplectic Geometry Seminar meeting in Berlin, see https://www.math.uni-hamburg.de/home/latschev/BH-symp.html |
| Monday July 7, 2025 13:15-14:45 RUD 25, Room 2.006 |
Speaker: Johannes Hauber Topic: TBA |
| Monday July 14, 2025 13:15-14:45 RUD 25, Room 2.006 |
Speaker: TBA Topic: TBA |