Date(s) : 02/02/2015 iCal
14 h 00 min - 15 h 00 min
The unlinking number of a link, i.e. of a disjoint collection of closed curves in S3, is defined as the minimal number of crossing changes required to turn the link into the trivial link. Determining the unlinking number of a given link is usually a hard problem. In particular there is no known algorithm for computing the unlinking number. We will present several techniques and results for finding lower bounds on the unlinking number. This is joint work with Maciej Borodzik, Jae Choon Cha and Mark Powell.