Takahiro Oba (Osaka University)

Title: A four-dimensional mapping class relation

Abstract: Relations between Dehn twists on mapping class groups of surfaces play an important role in the study of symplectic manifolds via Lefschetz fibrations. In higher dimensions, as little is known about symplectic mapping class groups, fibration-like structures are not so powerful yet. In this talk, I will give a relation between 4-dimensional Dehn twists on a symplectic 4-manifold. One of the key ingredients in the construction is a solution to the symplectic isotopy problem for symplectic surfaces in a Del Pezzo surface.