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Speaker:
Jennifer Hom
Zugehörigkeit:
Georgia Tech
Datum:
Mon, 17/10/2016 - 13:30 - 14:30
Location:
MPIM Lecture Hall
Parent event:
Conference on 4-manifolds and knot concordance The knot concordance group $\mathcal{C}$ consists of knots in $S^3$ modulo knots that bound smooth disks in $B^4$. We consider $\widehat{\mathcal{C}}_{\mathbb{Z}}$, the group of knots in homology spheres that bound homology balls modulo knots that bound smooth disks in a homology ball. Matsumoto asked if the natural map from $\mathcal{C}$ to $\widehat{\mathcal{C}}_{\mathbb{Z}}$ is an isomorphism. Adam Levine answered this question in the negative by showing the map is not surjective. We show that the image of $\mathcal{C}$ in $\widehat{\mathcal{C}}_{\mathbb{Z}}$ is of infinite index; more specifically, it contains a subgroup isomorphic to the integers. This is joint work with Adam Levine and Tye Lidman.
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