摘要

The sum-connectivity index is a newly proposed molecular descriptor defined as the sum of the weights of the edges of the graph, where the weight of an edge uv of the graph, incident to vertices u and v, having degrees d (u) and d (v) is (d (u) d (v) )(-1/2). We obtain the minimum sum-connectivity indices of trees and unicyclic graphs with given number of vertices and matching number, respectively, and determine the corresponding extremal graphs. Additionally, we deduce the n-vertex unicyclic graphs with the first and second minimum sum-connectivity indices for n a parts per thousand yen 4.