Conférencier: Patrick Orson, Boston College 

Résumé / Abstract: Knot traces are smooth 4-manifolds with boundary, that are homotopic to the 2-sphere, and obtained by attaching a 2-handle to the 4-ball along a framed knot in the 3-sphere. I will give a complete characterisation for when the generator of the second homotopy group of a knot trace can be represented by a locally flat embedded 2-sphere with abelian exterior fundamental group. The answer is in terms of classical and computable invariants of the knot. This is a joint project with Feller, Miller, Nagel, Powell, and Ray. 

Le lien pour se connecter est :  https://uqam.zoom.us/j/98999725241