Geometri och topologi: Froyshov-type invariants via homotopy theory
- Location: Ångströmlaboratoriet, Lägerhyddsvägen 1 64119
- Lecturer: Stefan Behrens (Bielefeld University)
- Contact person: Maksim Maydanskiy
Froyshov's h-invariants are numerical invariants of rational homology 3-spheres that appear in generalizations of Donaldson's diagonalizability theorem to 4-manifolds with boundary. They are defined in terms of the algebraic structure of monopole Floer homology. I will explain their relation to the primary obstructions in a series of extension problems that naturally arise in Manolescu's approach to Seiberg-Witten theory on 3-manifolds. The higher obstructions lead to refined, potentially stronger Froyshov-type invariants. This is joint work with Tyrone Cutler.