On Estrada index of trees
β Scribed by Jianbin Zhang; Bo Zhou; Jianping Li
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 230 KB
- Volume
- 434
- Category
- Article
- ISSN
- 0024-3795
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π SIMILAR VOLUMES
Let G be a simple graph of order n with m edges. Let the adjacency spectrum be {Ξ» 1 , Ξ» 2 , . . . In [J.A. PeΓ±a, I. Gutman, J. Rada, Estimating the Estrada index, Linear Algebra Appl. 427 (2007) 70-76], PeΓ±a et al. posed a conjecture that the star S n has maximum Estrada index for any tree of order
4, 6)-fullerene a b s t r a c t Suppose G is a graph and Ξ» 1 , Ξ» 2 , . . . Ξ» n are the eigenvalues of G. The Estrada index EE(G) of G is defined as the sum of the terms e Ξ» i , 1 β€ i β€ n. In this work some upper and lower bounds for the Estrada index of (4, 6)-fullerene graphs are presented.
The general sum-connectivity index of a graph G is defined as , where d u denotes the degree of vertex u in G, E(G) denotes the edge set of G, and Ξ± is a real number. We determine the maximum value for the general sum-connectivity indices of n-vertex trees and the corresponding extremal trees for Ξ±