SEMINAR: Groups and Combinatorics Seminar: Counting labelled delta-matroids

Time and place: 11:00 Friday 1 April in MLR1

Speaker: Steven Noble (Brunel University London)

Title: Counting labelled delta-matroids

Abstract: Delta-matroids were introduced and studied by Bouchet in the 1980s, but have largely been ignored until the last few years. They generalize matroids and include classes coming from embedded graphs and from symmetric matrices. This talk is based on recent joint work with Darryl Funk and Dillon Mayhew, in which we give bounds on the number of labelled delta-matroids with n elements. As expected there are many more delta-matroids than matroids, but the number of even delta-matroids, a class that is generally thought to behave more like matroids, is not so much larger than the number of matroids.