On light edges and triangles in projective planar graphs
Daniel P. Sanders · Journal of Graph Theory · 1996
An edge or face of an embedded graph is light if the sum of the degrees of the vertices incident with it is small. This paper parallelizes four inequalities on the number of light edges and light triangles from the plane to the projective plane. Each of the four inequalities is shown to be the best possible. © 1996 John Wiley & Sons, Inc.