Graph Theory – Planar Graphs: More or Less

graph theoryplanar-graphsterminology

A graph is planar if it can be drawn on the plane in such a way that its edges do not cross each other.

A graph is $k$-planar if it can be drawn on the plane in such a way that each of its edges is crossed at most $k$ times.

There is also a concept of almost planar graphs that relies on edge deletions or contractions.

I am dealing with another kind of graphs: they can be drawn in the plane in such a way that at most $k$ pairs of edges intersect.

Is there a terminology for such graphs?

Best Answer

These are the graphs with pairwise crossing number or pair-crossing number at most $k$. Note that it is an open problem whether the pair-crossing number is actually equal to the usual crossing number of a graph. See Crossing number, pair-crossing number, and expansion and The Graph Crossing Number and its Variants: A Survey for more info.

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