A polygon is a closed loop made up of straight line segments. When the loop does not intersect itself, the polygon is said to be a simple polygon. We can think of a simple polygon as a sequence of vertices specified in counter-clockwise order. Each vertex is a point with an (x,y) coordinate. For example, the simple polygon Q = {v0,v1,v2,v3,v4,v5,v6} in Figure 1(a) has 7 vertices and 7 edges.