Title: Nonisotopic splitting spheres for split surface links
Abstract: Given a split link in the 3-sphere, it can be shown that any two splitting spheres for the link are isotopic in its complement. In this talk I will outline a construction showing that this fact fails in dimension 4; I will show how to construct a surface unlink with nonisotopic splitting 3-spheres. Along the way I will show how a related construction can be used to obtain 3-dimensional handlebodies in the 4-sphere that are not isotopic rel boundary, even when pushed into the 5-ball. This is joint work with Seungwon Kim and Maggie Miller.