- τ-invariants for knots in rational homology spheres
- 09/11/2017
- 4:10 PM - 5:30 PM
- C304 Wells Hall
- Katherine Raoux, MSU
Using the knot filtration on the Heegaard Floer chain complex, Ozsváth and Szabó defined an invariant of knots in the 3-sphere called τ(K). In particular, they showed that τ(K) is a lower bound for the 4-ball genus of K. Generalizing their construction, I will show that for a (not necessarily null-homologous) knot, K, in a rational homology sphere, Y, we can define a collection of τ-invariants, one for each spin-c structure on Y. In addition, these invariants give a lower bound for the genus of a surface with boundary K properly embedded in a negative definite 4-manifold with boundary Y.