Buondì, Vi annuncio il seminario di geometria di domani. A presto, Bruno

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12-Dec-2019 - 16:15 Sala Seminari (Dip. Matematica) http://www.dm.unipi.it/webnew/it/aula/sala-seminari-dip-matematica Splitting numbers http://www.dm.unipi.it/webnew/it/seminari/splitting-numbers Carlo Collari NYU Abu Dhabi

The weak splitting number is the minimal number of crossing changes which are necessary to split the a link into a collection of disjoint knots. This invariant can be thought of as the (Gordian) distance between a link and the set of completely split links, and somehow as a measure of the complexity of a link. There is another version of the splitting number whose definition allows only crossing changes between different components.

In this talk we shall illustrate various methods to compute the weak splitting number and the splitting number. In particular, I shall give a template to produce lower bounds on the weak splitting number, and provide some examples. The material discussed in this talk is joint work with A. Cavallo and A. Conway.