Finite groups admitting a connected cubic integral bi-Cayley graph

Document Type : Research Paper

Authors

1 University of Larestan

2 Department of mathematical sciences Isfahan University of Technology Isfahan, Iran.

Abstract

A graph   is called integral if all eigenvalues of its adjacency matrix  are integers.  Given a subset $S$ of a finite group $G$, the bi-Cayley graph $BCay(G,S)$ is a graph with vertex set $G\times\{1,2\}$ and edge set $\{\{(x,1),(sx,2)\}\mid s\in S, x\in G\}$.  In this paper, we classify all finite groups admitting a connected cubic integral bi-Cayley graph.

Keywords


[1] A. Abdollahi and E. Vatandoost, Which Cayley graphs are integral? Electron. J. Combin. 16(1) (2009),
R122, pp. 1-17.
[2] M. Arezoomand and B. Taeri, On the characteristic polynomial of n-Cayley digraphs, Electron. J. Combin.
20(3) (2013), P57, pp. 1-14.
[3] M. Arezoomand and B. Taeri, Isomorphisms of nite semi-Cayley graphs, Acta Math. Sinica. Eng. Ser.,
31(4) (2015), pp. 715-730.
[4] M. Arezoomand and B. Taeri, A classi cation of nite groups with integral bi-Cayley graphs, Trans. Comb.,
4(4) (2015), pp. 55-61.
[5] N. Biggs, Algebraic Graph Theory, Cambridge University Press, (1974).
[6] M. Burrow, Representation theory of nite groups, Academic Press Inc., (1965).
[7] F. C. Bussemaker, D. Cvetkovic, There are exactly 13 connected, cubic, integral graphs, Univ. Beograd,
Publ. Elektrotehn. Fak. Ser. Mat. Fiz., Nos. 544-576 (1976), pp. 43-48.
[8] P. Diaconis and M. Shahshahani, Generating a random permutation with random transpositions, Z.Wahsch.
Verw. Gebiete, 57 (1981), pp. 159-179.
[9] F. Harary and A. J. Schwenk, Which graphs have integral spectra? in "Graphs and Combinatorics (Proc.
Capital Conf., George Washington Univ., Washington, D. C., 1973)", Lecture Notes in Mathematics 406.
Springer, Berlin, 1974, pp. 45-51.
[10] I. M. Isaacs, Character theory of nite groups, Academic Press, (1976).
[11] W. Jin and W. Liu, A classi cation of non-abelian simple 3-BCI-groups, Europ. J. Combin., 31 (2010), pp.
1257-1264.
[12] Z. P. Lu, C. Q. Wang, and M.Y. Xu, Semisymmetric cubic graphs constructed from bi-Cayley graphs of
An, Ars Combin. 80 (2006), pp. 177-187.
[13] A. J. Schwenk, Exactly thirteen connected cubic graphs have integral spectra, Theory and applications of
graphs (Proc. Internat. Conf., Western Mich. Univ., Kalamazoo, Mich., 1976), pp. 516-533, Lecture Notes
in Math., 642, Springer, Berlin, (1978).