设G是一个有限群,S是G的一个子集,Bi-Cayley图BC(G,S)是一个二部图:其顶点集为G×{0,1},而边集为{{(g,0),(sg,1)}:g∈G,s∈S}.本文研究了有限阿贝尔群G上的Cayley图D(G,S)和Bi-Calyley图BC(G,S)之间特征值的关系,并由此得到循环群上的Bi-Cayley图的特征值.继而得到生成树数的一些渐进性定理.
For a finite group G and a subset S(possibly, it contains the identity element) of G, the Bi-Cayley graph X = BC(G, S) of G with respect to S is defined as the bipartite graph with vertex set G ×(0, 1} and edge set {{(g,0), (sg, 1)}: g ∈ G, s∈ S}. In this paper, we investigate the relation between the eigenvalues of Cayley graph D(G, S) and Bi-Cayley graph BC(G, S) for a finite abelian group. As a consequence, we determine the eigenvalues of Bi-Cayley graphs of cyclic groups. In addition, some asymptotic enumeration theorems are presented.