Name  Yuanyuan Bao 

Affiliation  Tokyo Institute of Technology 
Talk type  Session 
Time  Jan 11 16:00~16:20 
Location  E11101 
Title  Finite negative unknotting number and Heegaard Floer homology 
Abstract 
If a knot can be transformed into the unknot by transforming finitely many positive crossings into negative crossings, we say this knot has finite negative unknotting number. Note that the sign of a crossing does not depend on the orientation of the knot. In particular, positive knots have finite negative unknotting number. In this talk, we give an obstruction for a knot to having finite negative unknotting number. This obstruction is derived from Heegaard Floer homology. We show some applications.

Slide  101111/slices_of_bao.pdf 