## Topology Seminar (Main Talk): Link homotopy in dimensions 4

Seminar | May 3 | 4:10-5 p.m. | 3 Evans Hall

Peter Teichner, UC Berkeley

Department of Mathematics

In the 4 pm talk, we'll present a joint result with Rob Schneiderman, to show that any link map of two 2-spheres in 4-space with one topologically embedded component is link homotopically trivial, implying that there is no 4-dimensional Hopf link. We'll use a 4-dimensional version of Milnor's elementary link homotopies as well as Freedman's disk embedding theorem.

hongbins@berkeley.edu