设i(G)是图G的Merrifield-Simmons指数.对图G1和G2,若i(G1)〈i(G2),则记G1〈G2.只有一个顶点的度I〉2的树称为似星树.对具有不同分枝的似星树的Merrifield-Simmons指数进行了比较,对具有相同分枝的似星树的Merrifield-Simmons指数进行了排序;并利用“〈”关系,刻画出了似星树关于Merrifield-Simmons指数的极图.
Let i(G) be the number of independent sets in the graph G. G1 〈G2 if i( G1 ) 〈 i(G2). A tree is said to be starlike if it possesses exactly one vertex of degree greater than two. The relation T1 〈 T2 is shown to hold for various pairs of starlike trees T1 , T2. The extremal starlike trees of order n with respect to the relation 〈 are characterized.