Berlin-Hamburg-Seminar am 17.2.2017

Tobias Ekholm (Uppsala)  Legendrian surgery formulas and duality between Lagrangian and Legendrian invariants

We give a Legendrian surgery formula for partially wrapped Floer cohomology and study (Koszul) duality between wrapped Floer cohomology and Floer cohomology using the surgery isomorphism. The talk reports on joint work with Y. Lekili.

Michael Hutchings (UC Berkeley, z.Z. HU Berlin)  Two or infinitely many Reeb orbits

Given a nondegenerate contact form on a closed connected three-manifold, such that the associated contact structure has torsion first Chern class, we prove that there are either two or infinitely many simple Reeb orbits. Combining this with previous results proves the existence of infinitely many simple Reeb orbits when the three-manifold is not the three-sphere or a lens space. Joint work with Dan Cristofaro-Gardiner and Dan Pomerleano.