Justin Sawon (Stony Brook) "Lagrangian fibrations on holomorphic symplectic fourfolds" Abstract: In this talk we will discuss holomorphic symplectic fourfolds (compact hyperkahler manifolds of real dimension eight) which admit fibrations by abelian surfaces. It is expected that every such fourfold can be deformed to such a fibration. We will describe some recent results on the polarization of the generic fibre and the degree of the discriminant locus parametrizing singular fibres. The motivation is to classify these Lagrangian fibrations and hence all holomorphic symplectic fourfolds.