In combinatorics, a thrackle is a graph formed by a collection of curves in the plane, with the property that the curves corresponding to any pair of edges meet in a single point, which is either an endpoint of both edges or a place where the two curves cross. Every planar straight line graph thrackle has at most as many edges as vertices; Conway's thrackle conjecture states that this is true even for curved thrackles. A thrackle also happens to be one of the coolest sounding things in mathematics, IMHO :0)

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