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On light edges and triangles in projective planar graphs. (English) Zbl 0854.05037
An edge of a graph is called light if the sum of the degrees of its vertices is $$\leq 11$$, or one vertex has degree 3 and sum of the degrees of its vertices is $$\leq 13$$. A triangle of a graph is called light if the sum of the degrees of its vertices is $$\leq 17$$. The paper under review adapts known inequalities on the number of light edges and light triangles in planar graphs to the analogous inequalities for graphs embedded in the projective plane.
Reviewer: M.Marx (Pensacola)

MSC:
 05C10 Planar graphs; geometric and topological aspects of graph theory
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