Degenerate Crossing Numbers
Pach, János ; Tóth, Géza
In: Discrete & Computational Geometry, 2009, vol. 41, no. 3, p. 376-384
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- Let G be a graph with n vertices and e≥4n edges, drawn in the plane in such a way that if two or more edges (arcs) share an interior point p, then they properly cross one another at p. It is shown that the number of crossing points, counted without multiplicity, is at least constant timese and that the order of magnitude of this bound cannot be improved. If, in addition, two edges are allowed to cross only at most once, then the number of crossing points must exceed constant times(e/n)4