The harmonic index of a graph G is defined as the sum of weights 2 deg(v)+deg(u) of all edges uv of E(G), where deg(v) denotes the degree of a vertex v in V (G). In this note we generalize results of [L. Zhong, The harmonic index on graphs, Appl. Math. Lett. 25 (2012), 561– 566] and establish some upper and lower bounds on the harmonic index of G.

The harmonic index of a graph G is defined as the sum of weights 2 d(u)+d(v) of all edges uv of G, where d(u) and d(v) are the degrees of the vertices u and v in G, respectively. In this paper, we determine the graph with minimum harmonic index among all unicyclic graphs with a perfect matching. Moreover, the graph with minimum harmonic index among all unicyclic graphs with a given matching num...

to evaluate the agronomic characteristics in three brassica species (rape, indian mustard, and turnip) and to determine the best stress tolerance indices, 16 brassica cultivars were studied under controlled conditions in -0.6 mpa of stress and as well under field (either stressed or irrigated) conditions at the dryland agricultural research station, kermanshah during 2004-05. the results showed...

The harmonic index H (G) of a graph G is defined as the sum of the weights 2 du+dv of all edges uv of G, where du denotes the degree of a vertex u in G. In this paper, we determine (i) the trees of order n and m pendant vertices with the second smallest harmonic index, (ii) the trees of order n and diameter r with the smallest and the second smallest harmonic indices, and (iii) the trees of ord...