A New Like Quantity Based on "Estrada Index"
نویسندگان
چکیده
منابع مشابه
New Lower Bounds for Estrada Index
Let G be an n-vertex graph. If λ1, λ2, . . . , λn are the adjacency eigenvalues of G, then the Estrada index and the energy of G are defined as EE(G) = ∑n i=1 e λi and E(G) = ∑n i=1 |λi|, respectively. Some new lower bounds for EE(G) are obtained in terms of E(G). We also prove that if G has m edges and t triangles, then EE(G) ≥ √ n2 + 2mn+ 2nt. The new lower bounds improve previous lower bound...
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If G is an (n,m)-graph whose spectrum consists of the numbers λ1, λ2, . . . , λn, then its Estrada index is EE(G) = ∑n i=1 e λi . We establish lower bounds for EE(G) in terms of n and m. Introduction In this paper we are concerned with simple graphs, that have no loops and no multiple or directed edges. Let G be such a graph, and let n and m be the number of its vertices and edges. Then we say ...
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Let G be a simple connected graph on n vertices and λ1, λ2, . . . , λn be the eigenvalues of the adjacency matrix of G. The Estrada index of G is defined as EE(G) = Σ i=1 ei . A cactus is a connected graph in which any two cycles have at most one common vertex. In this work, the unique graph with maximal Estrada index in the class of all cacti with n vertices and k cycles was determined. Also, ...
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A structure-descriptor EE, recently proposed by Estrada, is examined. If λ1, λ2, . . . ,λn are the eigenvalues of the molecular graph, then EE = n ∑ i=1 eλi . In the case of benzenoid hydrocarbons with n carbon atoms and m carbon-carbon bonds, EE is found to be accurately approximated by means of the formula a1 n cosh (√ 2m/n ) +a2, where a1 ≈ 1.098 and a2 =−0.64 are empirically determined fitt...
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ژورنال
عنوان ژورنال: Journal of Inequalities and Applications
سال: 2010
ISSN: 1029-242X
DOI: 10.1155/2010/904196