A lower bound for the harmonic index of a graph with minimum degree at least two

被引:61
|
作者
Wu, Renfang [1 ]
Tang, Zikai [1 ]
Deng, Hanyuan [1 ]
机构
[1] Hunan Normal Univ, Minist Educ China, Coll Math & Comp Sci, Key Lab High Performance Comp & Stochast Informat, Changsha 410081, Hunan, Peoples R China
关键词
Graph; the harmonic index; the minimum degree;
D O I
10.2298/FIL1301051W
中图分类号
O29 [应用数学];
学科分类号
070104 ;
摘要
The harmonic index H(G) of a graph G is defined as the sum of the weights 2/ d(u)+ d(v) of all edges uv of G, where d(u) denotes the degree of a vertex u in G. We give a best possible lower bound for the harmonic index of a graph (a triangle-free graph, respectively) with minimum degree at least two and characterize the extremal graphs.
引用
收藏
页码:51 / 55
页数:5
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