Universitat, Bielefeld, Germany
A got obsessed with smooth 4-manifolds early on. First came exotic $\mathbb R^4$'s, came Donaldson's diagonalizability theorem. In a way, I'm still obsessed with the latter in the form of Froyshov invariants in Seiberg-Witten theory and correction terms in Heegaard-Floer theory. Putting some order into these things has been keeping me busy.
Apart from that, I'm interested in almost anything that passes as low dimensional topology and Floer theory, much that passes as differential topology, and I've also been getting curious about equivariant and stable homotopy theory, mostly in relation to Floer theory.