2008/01/14 by Hall, Rhiannon, Mayhew, Dillon
#05B35 #Combinatorics (math.CO) #FOS: Mathematics
paper · doi:10.48550/arxiv.0801.2010
We consider the situation that M and N are 3-connected matroids such that |E(N)| > 3 and C* is a cocircuit of M with the property that M/y has an N-minor for some y in C*. We show that either there is an element x in C* such that si(M/x) or co(si(M/x)) is 3-connected with an N-minor, or there is a four-element fan of M that contains two elements of C* and an element x such that si(M/x) is 3-connected with an N-minor.