Except for triangles every simple polygon has at least two non overlapping ears. A good sub polygon of a simple polygon P, denoted by GSP, is a sub polygon whose boundary differs from that of P in at most one edge. Consider Step 2. Two Ears Theorem was motivated by the problem of triangulating a simple polygon. In fact Meisters suggests a greedy, but concise algorithm to achieve this goal, i.e. find an ear and cut it off.
Polygons have ears .
American Mathematical Monthly. We present an algorithm that triangulates a polygon by searching for ears and clipping them. Section 6 reports on tests and experiments for determining the practical reliability of the code. The paper is concluded in Section 7. Most early triangulation algorithms try to find a diagonal of the polygon and then recurse on the two resulting sub polygons.