The quotients between the (revised) Szeged index and Wiener index of graphs

Jing Chen, Shuchao Li, Huihui Zhang

Published 2016-06-20Version 1

Let $Sz(G),Sz^*(G)$ and $W(G)$ be the Szeged index, revised Szeged index and Wiener index of a graph $G.$ In this paper, the fourth, fifth, sixth and seventh largest Wiener indices among all unicyclic graphs of order $n\geq 10$ are determined, respectively, as well the first, second, third, and fourth largest Wiener indices among all bicyclic graphs of order $n\geq 7$ are determined, respectively. All the corresponding extremal graphs are identified. Based on these results, further relation on the quotients between the (revised) Szeged index and the Wiener index are studied. Sharp lower bound on $Sz(G)/W(G)$ is determined for all connected graphs each of which contains at least one non-complete block. As well the connected graph with the second smallest value on $Sz^*(G)/W(G)$ is identified for $G$ containing at least one cycle.