Title
On Harary index of graphs
Abstract
The Harary index is defined as the sum of reciprocals of distances between all pairs of vertices of a connected graph. For a connected graph G=(V,E) and two nonadjacent vertices v"i and v"j in V(G) of G, recall that G+v"iv"j is the supergraph formed from G by adding an edge between vertices v"i and v"j. Denote the Harary index of G and G+v"iv"j by H(G) and H(G+v"iv"j), respectively. We obtain lower and upper bounds on H(G+v"iv"j)-H(G), and characterize the equality cases in those bounds. Finally, in this paper, we present some lower and upper bounds on the Harary index of graphs with different parameters, such as clique number and chromatic number, and characterize the extremal graphs at which the lower or upper bounds on the Harary index are attained.
Year
DOI
Venue
2011
10.1016/j.dam.2011.06.003
Discrete Applied Mathematics
Keywords
Field
DocType
diameter,extremal graph,equality case,chromatic number,clique number,different parameter,graph,connected graph,harary index,nonadjacent vertices v,vertices v,upper bound,indexation
Graph,Discrete mathematics,Clique number,Combinatorics,Vertex (geometry),Bound graph,Epigraph,Connectivity,New digraph reconstruction conjecture,Mathematics
Journal
Volume
Issue
ISSN
159
15
Discrete Applied Mathematics
Citations 
PageRank 
References 
7
0.78
6
Authors
3
Name
Order
Citations
PageRank
Kexiang Xu17211.43
Kinkar Ch. Das220830.32
Nenad Trinajstic333067.57