ABSTRACT
Ear A PRINCIPAL VERTEX xi of a SIMPLE POLYGON P is called an ear if the diagonal [xi1; xi1] that bridges xi lies entirely in P . Two ears xi and xj are said to overlap if
int[xi1; xi; xi1]S int[xj1; xj; xj1]"¥:
The TWO-EARS THEOREM states that, except for TRIANGLES, every SIMPLE POLYGON has at least two nonoverlapping ears.
