João Faria Martins
CMA e FCT/UNL

Abstract: Motivated by recently discovered connections to topological phases of matter of condensed matter Physics / topological quantum computing, I will describe work I have done some years ago oninvariants of knotted surfaces embedded in the 4-sphere derived from finite crossed modules. I will also report on oneiric (at this moment) extensions of this framework to Lie crossed modules invariants of knotted surfaces, to be addressed in the realm of gerbes and categorified BF-theories.

This seminar is supported by National Funding from FCT - Fundação para a Ciência e a Tecnologia, under the project: UID/MAT/04561/2013.