On the number of radial orderings of planar point sets

José M. Díaz-Bañez, Ruy Fabila-Monroy, Pablo Pérez-Lantero

Given a set $S$ of $n$ points in the plane, a \emph{radial ordering} of $S$ with respect to a point $p$ (not in $S$) is a clockwise circular ordering of the elements in $S$ by angl…