ON THE SPECTRAL MOMENT OF GRAPHS WITH GIVEN CLIQUE NUMBER

Let L-n,L-t be the set of all nvertex connected graphs with clique number t (2 <= t <= n). For n-vertex connected graphs with given clique number, lexicographic ordering by spectral moments (Sorder) is discussed in this paper. The first Sigma([(n-t-1)/3])(i=1)(n-t-3i) + 1 graphs with 3 <= t <= n-4, and the last few graphs, in the S-order, among are characterized. In addition, all graphs in Ln,nULn,n-1 have an S-order; for the cases t = n-2 and t = n-3, the first three and the first seven graphs in the set L-n,L-t are characterized, respectively.