Date(s) : 24/10/2016 iCal
14 h 00 min - 15 h 00 min
The homology groups of a manifold give a lower bound on the number of handles in a handle decomposition (or even on the cells of a CW decomposition). We use Casson-Gordon signatures to improve on this bound for rational homology 4-balls bounding a given rational homology 3-sphere. In turn, this gives information about slice and ribbon discs for knots in the 3-sphere.
This is joint work (in progress) with Paolo Aceto and Ana Lecuona.