Constructing locally flat surfaces in 4-manifolds (part 2)

There are two main approaches to building locally flat surfaces in 4-manifolds: direct methods applying Freedman-Quinn's disc embedding theorem, and indirect methods using surgery theory. (Notably the second method also requires the disc embedding theorem, but only indirectly.) In this sequence of two lectures, I will give an introduction to both methods. In this second lecture I will give a surgery-theoretic proof of a result of Freedman-Quinn, which states that every Alexander polynomial one knot is topologically slice.