The Catalan numbers also count the number of ways in which ann-gon can be dissected into triangles by nonintersecting diagonals.
加泰隆数又是用不相交的对角线划分几边形成三角形的方式数。
2
Let P and Q be two nonintersecting simple polygons in the plane, this paper discusses the rotational movability of them if P rotates around a point and collides with Q .