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Session S28 - Knots, Surfaces, 3-manifolds

Friday, July 23, 16:40 ~ 17:10 UTC-3

Instantons and Knot Concordance

Juanita Pinzón Caicedo

University of Notre Dame, USA   -   This email address is being protected from spambots. You need JavaScript enabled to view it.

Knot concordance can be regarded as the study of knots as boundaries of surfaces embedded in spaces of dimension 4. Specifically, two knots $K_0$ and $K_1$ are said to be smoothly concordant if there is a smooth embedding of the annulus $S^1 \times [0, 1]$ into the ``cylinder'' $S^3 \times [0, 1]$ that restricts to the given knots at each end. Smooth concordance is an equivalence relation, and the set $\mathcal{C}$ of smooth concordance classes of knots is an abelian group with connected sum as the binary operation. The algebraic structure of $\mathcal{C}$, the concordance class of the unknot, and the set of knots that are topologically slice but not smoothly slice are much studied objects in low-dimensional topology. Gauge theoretical results on the nonexistence of certain definite smooth 4-manifolds can be used to better understand these objects. In particular, the study of anti-self dual connections on 4-manifolds can be used to shown that (1) the group of topologically slice knots up to smooth concordance contains a subgroup isomorphic to $\mathbb{Z}^\infty$, and (2) satellite operations that are similar to cables are not homomorphisms on $\mathcal{C}$.

Joint work with Matt Hedden (Michigan State University, USA) and Tye Lidman (North Carolina State University, USA).

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