Mon, July 20, 3pm ET (8pm BST, 7am Tue NZST)
Pascal Gollin, Institute for Basic Science
Obstructions for bounded branch-depth in matroids
Youtube

Abstract:
DeVos, Kwon, and Oum introduced the concept of branch-depth of matroids as a natural analogue of tree-depth of graphs. They conjectured that a matroid of sufficiently large branch-depth contains the uniform matroid $U_{n,2n}$ or the cycle matroid of a large fan graph as a minor. In this talk, I present a proof that matroids of sufficiently large branch-depth either contain the cycle matroid of a large fan graph as a minor or have large branch-width.

This is joint work with Kevin Hendrey, Dillon Mayhew and Sang-il Oum.