The blocker number of simple drawings of complete graphs

A drawing of a graph represents vertices by distinct plane points and edges by simple curves, with a vertex meeting an edge only at an endpoint. A drawing is simple if any two edges intersect at most once, either at a common endpoint or at a proper crossing. A set of points blocks a drawing if it contains no vertex and every edge contains a blocker. Simple-drawing blocker conjecture. The minimum number of blockers in a simple drawing of $K_n$ equals $2n-3$. A construction gives an upper bound of $2n-3$, while the general lower bound stated in the source is only $n-1$; the conjectured exact value remains open.