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Speaker:

Alexandra Kjuchukova
Affiliation:

University of Wisconsin-Madison/MPIM
Date:

Tue, 17/09/2019 - 10:30 - 10:55
Location:

MPIM Lecture Hall
Parent event:

Workshop on 4-manifolds, September 16 - 20, 2019 Let $K$ be a knot with the property that $\pi_1(S^3\backslash K)$ surjects onto a dihedral group. I will define a ribbon obstruction for $K$, given a cover of $S^4$ branched along a surface embedded smoothly in $S^4$ except for one cone singularity, the cone on $K$. I will give examples of knots whose non-ribbonness can be detected by this method, and I will state a few results in the subject. Based on joint works with Cahn, Geske, Orr, Shaneson.

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