Spectral aspects of commuting conjugacy class graph of finite groups

Document Type : Research Paper

Authors

1 Department of Mathematical Sciences, Tezpur university, Napaam Assam, India.

2 Department of Mathematical Sciences, Tezpur University, Sonitpur, India

Abstract

The commuting conjugacy class graph of a non-abelian group G, denoted by CCC(G), is a simple undirected graph whose vertex set is the set of conjugacy classes of the non-central elements of G and two distinct vertices xG and yG are adjacent if there exists some elements xxG and yyG such that xy=yx. In this paper we compute various spectra and energies of commuting conjugacy class graph of the groups D2n,Q4m,U(n,m),V8n and SD8n. Our computation shows that CCC(G) is super integral for these groups. We compare various energies and as a consequence it is observed that CCC(G) satisfy E-LE Conjecture of Gutman et al. We also provide negative answer to a question posed by Dutta et al. comparing Laplacian and Signless Laplacian energy. Finally, we conclude this paper by characterizing the above mentioned groups G such that CCC(G) is hyperenergetic, L-hyperenergetic or Q-hyperenergetic.

Keywords


[1] N. M. M. Abreu, C. T. M. Vinagre, A. S. Bonif_acioa and I. Gutman, The Laplacian energy of some Laplacian integral graph, MATCH Commun. Math. Comput. Chem., 60 (2008) 447-460.
[2] K. Balińska, D. Cvetković, Z. Radosavljević, S. Simić and D. Stevanović, A survey on integral graphs, Univ. Beograd. Publ. Elektrotehn. Fak. Ser. Mat., 13 (2003) 42-65.
[3] R. Brauer and K. A. Fowler, On groups of even order, Ann. of Math., 62 No. 2 (1955) 565-583.
[4] D. Cvetković, P. Rowlinson, S. Simić, Signless Laplacian of finite graphs, Linear Algebra Appl., 423 (2007) 155-171.
[5] P. Dutta, B. Bagchi and R. K. Nath, Various energies of commuting graphs of finite nonabelian groups, Khayyam J. Math., 6 No. 1 (2020) 27-45.
[6] J. Dutta and R. K. Nath, Spectrum of commuting graphs of some classes of finite groups, Matematika, 33 No. 1 (2017) 87-95.
[7] J. Dutta and R. K. Nath, Finite groups whose commuting graphs are integral, Mat. Vesnik, 69 No. 3 (2017) 226-230.
[8] J. Dutta and R. K. Nath, Laplacian and signless Laplacian spectrum of commuting graphs of finite groups, Khayyam J. Math., 4 No. 1 (2018) 77-87.
[9] W. N. T. Fasfous, R. K. Nath and R. Sharafdini, Various spectra and energies of commuting graphs of finite rings, Hacet. J. Math. Stat., 49 No. 6 (2020) 1915-1925.
[10] S.C. Gong, X. Li, G.H. Xu, I. Gutman and B. Furtula, Borderenergetic graphs, MATCH Commun. Math. Comput. Chem., 74 (2015) 321-332.
[11] I. Gutman, Hyperenergetic molecular graphs, J. Serb. Chem. Soc., 64 (1999) 199-205.
[12] I. Gutman, N. M. M. Abreu, C. T. M. Vinagre, A. S. Bonifácioa and S. Radosavljević, Relation between energy and Laplacian energy, MATCH Commun. Math. Comput. Chem., 59 (2008) 343-354.
[13] F. Harary and A. J. Schwenk, Which graphs have integral spectra?, Graphs and Combin., Lect. Notes Math., 406 (1974), Springer-Verlag, Berlin, 45-51.
[14] M. Herzog, M. Longobardi and M. Maj, On a commuting graph on conjugacy classes of groups. Comm. Algebra, 37 No. 10 (2009) 3369-3387.
[15] S. Kirkland, Constructably Laplacian integral graphs, Linear Algebra Appl., 423 (2007) 3-21.
[16] J. Liu, and B. Liu, On the relation between energy and Laplacian energy, MATCH Commun. Math. Comput. Chem., 61 (2009) 403-406.
[17] R. Merris, Degree maximal graphs are Laplacian integral, Linear Algebra Appl., 199 (1994) 381-389.
[18] A. Mohammadian, A. Erfanian, D. G. M. Farrokhi and B. Wilkens, Triangle-free commuting conjugacy class graphs. J. Group Theory, 19 (2016) 1049-1061.
[19] R. K. Nath, Various spectra of commuting graphs n-centralizer finite groups, International Journal of Engineering Science and Technology, accepted for publication.
[20] M. A. Salahshour and A. R. Ashrafi, Commuting conjugacy class graph of finite CA-groups, Khayyam J. Math., 6 No. 1 (2020) 108-118.
[21] S. K. Simić and Z. Stanić, Q-integral graphs with edge-degrees at most five, Discrete Math., 308 (2008) 4625-4634.
[22] D. Stevanović, I. Stanković, and M. Milošević, More on the relation between energy and Laplacian energy, MATCH Commun. Math. Comput. Chem., 61 (2008) 395-401.
[23] F. Tura, L-borderenergetic graphs, MATCH Commun. Math. Comput. Chem., 77 (2017) 37-44.
[24] H.B. Walikar, H.S. Ramane and P.R. Hampiholi, On the energy of a graph, Graph Connections, Allied Publishers, New Delhi, 1999, pp. 120-123, Eds. R. Balakrishnan, H. M. Mulder, A. Vijayakumar.