Harmonic index and harmonic polynomial on graph operations

Some years ago, the harmonic polynomial was introduced to study the harmonic topological index. Here, using this polynomial, we obtain several properties of the harmonic index of many classical symmetric operations of graphs: Cartesian product, corona product, join, Cartesian sum and lexicographic product. Some upper and lower bounds for the harmonic indices of these operations of graphs, in terms of related indices, are derived from known bounds on the integral of a product on nonnegative convex functions. Besides, we provide an algorithm that computes the harmonic polynomial with complexity O(n 2 ).This work was supported in part by two grants from Ministerio de Economía y Competititvidad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) (MTM2016-78227-C2-1-P and MTM2017-90584-REDT), Spain

f-polynomial on some graph operations

Given any function f:Z+→R+ , let us define the f-index If(G)=∑u∈V(G)f(du) and the f-polynomial Pf(G,x)=∑u∈V(G)x1/f(du)−1, for x>0 . In addition, we define Pf(G,0)=limx→0+Pf(G,x) . We use the f-polynomial of a large family of topological indices in order to study mathematical relations of the inverse degree, the generalized first Zagreb, and the sum lordeg indices, among others. In this paper, using this f-polynomial, we obtain several properties of these indices of some classical graph operations that include corona product and join, line, and Mycielskian, among others.Supported in part by two grants from the Ministerio de Economía y Competititvidad, Agencia Estatal de Investigación (AEI), and Fondo Europeo de Desarrollo Regional (FEDER) (MTM2016-78227-C2-1-P and MTM2017-90584-REDT), Spain

Topological indices and f-polynomials on some graph products

We Obtain Inequalities Involving Many Topological Indices In Classical Graph Products By Using The F-Polynomial. In Particular, We Work With Lexicographic Product, Cartesian Sum And Cartesian Product, And With First Zagreb, Forgotten, Inverse Degree And Sum Lordeg Indices.Gobierno de Españ