On the spectral moments of unicyclic graphs with fixed diameter

Abstract: Unicyclic graphs are connected graphs in which the number of edges equals the number of vertices. Let be the class of unicyclic graphs of order n and diameter d. For unicyclic graphs, lexicographic ordering by spectral moments (S-order) is discussed in this paper. The last graphs, in the S-order, among all unicyclic graphs in are characterized. In addition, for the cases and , the last and last unicyclic graphs in the set are also given, respectively. [Copyright &y& Elsevier]