Thursday, January 21, 2016, 10:20 am.

Title: Ribbon graphs and Delta-matroids.

Abstract.
It usual tot think about the matroid theory as a generalization of graph theory. 
I will explain an analogous correspondence between graphs embedded into a surface 
and Delta-matroids: embedded graphs naturally determine Delta-matroids. I will show 
that a natural topological operation on ribbon graphs, the partial duality, can be 
interpreted as classical twist of Delta-matroids. Also, I will show that topological 
version of the Tutte polynomial for ribbon graph are in fact delta-matroidal.If time 
permit, I will show applications of this to the knot theory. In large part the talk 
will be based on the preprint  arXiv:1403.0920 [math.CO] "Matroids, Delta-matroids 
and Embedded Graphs" by C.Chun, I.Moffatt, S.Noble, R.Rueckriemen.