Online talk: Daryl Funk

Monday, April 12, 3pm ET (8pm BST, 7am Tue NZST)
Daryl Funk, Douglas College
The class of bicircular matroids has only a finite number of excluded minors

Zoom: https://us02web.zoom.us/j/82901072811 (**new zoom link**)
Password: email rose.mccarty ~at~ uwaterloo ~.~ ca if you need the password
 
Abstract:

We show that the class of bicircular matroids has only a finite number of excluded minors. Key tools used in our proof include representations of matroids by biased graphs and the recently introduced class of quasi-graphic matroids. We show that if $N$ is an excluded minor of rank at least eight, then $N$ is quasi-graphic. Several small excluded minors are quasi-graphic. Using biased-graphic representations, we find that $N$ already contains one of these. We also provide an upper bound, in terms of rank, on the number of elements in an excluded minor, so the result follows.

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