English

On the spectral moment of trees with given degree sequences

Combinatorics 2012-09-12 v1

Abstract

Let A(G)A(G) be the adjacency matrix of graph GG with eigenvalues λ1(G),λ2(G),...,λn(G)\lambda_1(G), \lambda_2(G),..., \lambda_n(G) in non-increasing order. The number Sk(G):=i=1nλik(G)(k=0,1,...,n1)S_k(G):=\sum_{i=1}^{n}\lambda_i^{k}(G)\, (k=0, 1,..., n-1) is called the kkth spectral moment of GG. Let S(G)=(S0(G),S1(G),...,Sn1(G))S(G) = (S_0(G), S_1(G),..., S_{n-1}(G)) be the sequence of spectral moments of G.G. For two graphs G1,G2G_1, G_2, we have G1sG2G_1\prec_{s}G_2 if for some k{1,2,3,...,n1}k \in \{1,2,3,...,n-1\}, we have Si(G1)=Si(G2),i=0,1,...,k1S_i(G_1) = S_i(G_2)\, ,\, i = 0, 1,..., k-1 and Sk(G1)<Sk(G2).S_k(G_1)<S_k(G_2). In this paper, the last nn-vertex tree with a given degree sequence in an SS-order is determined. Consequently, we also obtain the last trees in an SS-order in the sets of all trees of order nn with the largest degree, the leaves number, the independence number and the matching number, respectively.

Keywords

Cite

@article{arxiv.1209.2188,
  title  = {On the spectral moment of trees with given degree sequences},
  author = {Li Shuchao and Song Yibing},
  journal= {arXiv preprint arXiv:1209.2188},
  year   = {2012}
}

Comments

9 pages; 1 figure