On the harmonic index of graph operations

‎‎The harmonic index of a connected graph G‎, ‎denoted by H(G)‎, ‎is‎ ‎defined as H(G)=\sum_{uv\in E(G)}\frac{۲}{d_u+d_v}‎ ‎where d_v is the degree of a vertex v in G‎. ‎In this paper‎, ‎expressions for the Harary indices of the‎ ‎join‎, ‎corona product‎, ‎Cartesian product‎, ‎composition and symmetric difference of graphs are‎ ‎derived‎.  

کلیدواژه ها:

harmonic index ، Graph operations ، Topological indices ، graphs