Benjamin Audoux (Aix-Marseille Université)
In this talk, I will introduce cut-diagrams, a combinatorial data which generalizes welded links to higher dimensions. Using them, I will give and discuss then Chen-Milnor presentations for the nilpotent and reduced fundamental groups of knotted surfaces. This is joint work in progress with J-B. Meilhan and A. Yasuhara.
, a link in a homology sphere is called slice if it bounds a disjoint union of locally flat embedded disks in a contractible 4-manifold. It is trivial to see that any link in