Separating Bichromatic Point Sets By Minimal Triangles With A Fixed Angle

Given a set P of red points and a set Q of blue points in the plane, of total size n, we investigate the problem of finding triangles with a given angle. that ( a) contain all points of Q, (b) avoid all points of P, and (c) are minimal, i.e. their three sides are tangent to the convex hull of Q. Such triangles are called minimal separating. theta-triangles. We give an algorithm for reporting all combinatorially different minimal separating.theta-triangles in O(n log n) time.