Title: Equivariant Concordance of Periodic 2-Knots

Speaker: Remy Bohm, UT Austin

Abstract: It has been known since the '60's that all 2-knots are slice, meaning that all 2-spheres embedded in the 4-sphere bound embedded 3-balls into the 5-ball, and thus are concordant to the unknotted sphere. However, when we restrict to the class of "periodic" 2-knots, meaning 2-knots which are invariant under a certain Z/dZ symmetry of the 4-sphere, there are actually two concordance classes. In this talk, we'll discuss the technique used by Kervaire to slice 2-knots, and then illustrate an invariant which completely classifies periodic 2-knots up to equivariant concordance.