Seminars in geometry/topology

August 27, 13:15 - 14:15, room 734, Sentralbygg 2

Mark Powell (Durham/UQAM): The 4-dimensional sphere embedding theorem

Abstract: I will describe the classification by Freedman of simply connected 4-dimensional topological manifolds, with emphasis on use of the sphere embedding theorem in its proof. Arunima Ray, Peter Teichner and I found that a technical improvement to Freedman's main embedding theorem is necessary in order to apply the theorem to 4-manifold classification, and I will endeavour to explain this new ingredient.