On the Crossing Number of Kn without Computer Assistance
Dan McQuillan, R. Bruce Richter · Journal of Graph Theory · 2015
We present several general results about drawings of , as a beginning to trying to determine its crossing number. As application, we give a complete proof that the crossing number of K9 is 36 and that all drawings in one large, natural class of drawings of K11 have at least 100 crossings.