圖形G＝（V,E）中獨立集為點集V之一子集合S，且使得S中任兩點在G中均不相連。在本篇論文中，我們以另一種較簡易方法得到樹圖中獨立集個數的最大、第二大、最小及第二小數值等已知的結果。除此之外，我們亦描繪出達到這些數值之所有極圖。

In a graph G=(V, E), an independent set is a subset S of V such that no two vertices in S are adjacent. In this paper, we will give alternative proofs for the solutions to readily determine the largest, second largest and the smallest, second smallest number of independent sets among all trees. Extremal graphs achieving these values are also given.