topological graphs with no self-intersecting cycle of length 4
Let G be a topological graph on n vertices in the plane, i.e., a graph drawn in the plane with its vertices represented as points and its edges represented as Jordan arcs connecting pairs of points. It is shown that if no two edges of any cycle of length 4 in G cross an odd number of times, then |E(G)|=O(n 8/5 ) .
topological graphs self-intersecting cycle extremal graph theory