21 research outputs found
The quotients between the (revised) Szeged index and Wiener index of graphs
Let and be the Szeged index, revised Szeged index and
Wiener index of a graph In this paper, the graphs with the fourth, fifth,
sixth and seventh largest Wiener indices among all unicyclic graphs of order
are characterized; as well the graphs with the first, second,
third, and fourth largest Wiener indices among all bicyclic 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 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 is identified for containing at least one
cycle.Comment: 25 pages, 5 figure
Five results on maximizing topological indices in graphs
In this paper, we prove a collection of results on graphical indices. We
determine the extremal graphs attaining the maximal generalized Wiener index
(e.g. the hyper-Wiener index) among all graphs with given matching number or
independence number. This generalizes some work of Dankelmann, as well as some
work of Chung. We also show alternative proofs for two recents results on
maximizing the Wiener index and external Wiener index by deriving it from
earlier results. We end with proving two conjectures. We prove that the maximum
for the difference of the Wiener index and the eccentricity is attained by the
path if the order is at least and that the maximum weighted Szeged
index of graphs of given order is attained by the balanced complete bipartite
graphs.Comment: 13 pages, 4 figure