|Time||Jan 11 13:50~14:30|
|Title||Concordance class of the Hopf link|
Extending the work of M. Freedman on knot concordance, J. Davis showed that a 2-component link with (2-variable) Aelxander polynomial one is topologically concordant to the Hopf link. In this talk, answering a question of J, Davis, we show that there is a 2-component link with Alexander polynomial one and unknotted components that is not smoothly concordant to the Hopf link. We will discuss the key ingredients of the proof such as covering link calculus, blow-down for links and knot concordance invariants from Heegaard-Floer theory. This is joint work with Jae Choon Cha, Daniel Ruberman and Saso Strle.