四元素链是由若干个单位正方形序列且任意相邻两个正方形只有一个公共顶点构成的连通图。本文主要研究了n个单位正方形序列构成的四元素链在两种不同构联接位下的Merrifield—Simmons指标,并给出其计算公式。
Four-membered chains is a connected graph that consists of several unit square sequences and any two adjacent square have only one common vertex, this paper presents the Merrifield-Sirnmons index and its calculation formula of four-membered chains made up by nunit square sequences under two don't isomorphic connected positions.