Vertices of Degree 6 in Contraction-Critical 6 Connected Graphs
Xudong Yuan · Guangxi kexue · 2006
It is proved that for each vertex x of degree 6 in a contraction-critical connected graph either there is a neighbor of degree 6 of x,or there exists a vertex y in N(x) such that there are two adjacent vertices of degree 6 in the neighborhood of y.