A thrackle is a good drawing in which every pair of distinct edges meets exactly once, either at a common endpoint or at a proper graph crossing. A graph is thrackleable if it admits such a drawing. The Conway thrackle conjecture asserts that a thrackle has no more edges than vertices.
Thrackle
See also
Conway Thrackle Conjecture, Good Drawing, Graph Crossing Number, Graph DrawingExplore with Wolfram|Alpha
References
Scoppetto, T. "Another Brick in the Wall: A Computationally Assisted Proof of an Improved Upper Bound for Thrackles." 13 Oct 2026. https://arxiv.org/abs/2610.17508.Cite this as:
Weisstein, Eric W. "Thrackle." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Thrackle.html