Let G be a graph on n vertices, and let CHP(G; Ξ») be the characteristic polynomial of its adjacency matrix A(G). All n roots of CHP(G; Ξ»), denoted by Ξ» i (i = 1, 2, . . . n), are called to be its eigenvalues. The energy E(G) of a graph G, is the sum of absolute values of all eigenvalues, namely, E(G
Minimizing a class of unicyclic graphs by means of Hosoya index
β Scribed by Hongbo Hua
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 481 KB
- Volume
- 48
- Category
- Article
- ISSN
- 0895-7177
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β¦ Synopsis
The Hosoya index, denoted by z(G), of a (molecular) graph G is defined as the total number of independent-edge sets of G. Let U n be the set of unicyclic graphs with n vertices. A fully loaded unicyclic graph is a unicyclic graph with the property that there is no vertex with degree less than 3 in its unique cycle. Denote by U 1 n the set of fully loaded unicyclic graphs. In this paper, graphs in U 1 n with minimal, second-minimal and third-minimal Hosoya indices are uniquely determined, respectively.
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