(Un)knotted nullhomotopic spheres and disks in 4-manifolds
Vendredi, 14 Octobre, 2022 - 10:30 à 11:30
Two smoothly embedded surfaces in a 4-manifold are called exotic if they are C^0 ambient isotopic without being smoothly equivalent.
In the talk, I will briefly introduce this peculiar phenomenon and show how it is possible to construct an infinite family of pairwise exotic 2-knots (embedded spheres) in a smooth 4-manifold. Furthermore we will see that these examples bound a topologically embedded 3-ball but not a smoothly embedded one. Finally, the disks obtained by removing a ball from the ambient manifold are, in some sense, exotic.The talk is based on a joint work with Benyahia and Torres (see https://arxiv.org/abs/2206.09659).
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