On Donaldson's flow of surfaces in a hyperkahler four-manifold

We prove some basic properties of Donaldson’s flow of surfaces in a hyperkahler 4-manifold. When the initial submanifold is symplectic with respect to one K"ahler form and Lagrangian with respect to another, we show that certain kinds of singularities cannot form, and we prove a convergence result under a condition related to one considered by M.-T. Wang for the mean curvature flow.