Abstract
A graph is Cartesian decomposable if it is isomorphic to a Cartesian product of strictly smaller graphs, each of which has more than one vertex and admits no such decomposition. These smaller graphs are called the Cartesian-prime factors of the Cartesian decomposition, and were shown, by Sabidussi and Vizing independently, to be uniquely determined up to isomorphism. We characterise by their parameters those generalised Paley graphs which are Cartesian decomposable, and we prove that for such graphs, the Cartesian-prime factors are themselves smaller generalised Paley graphs. This generalises a result of Lim and the second author which deals with the case where all the Cartesian-prime factors are complete graphs. These results contribute to the determination, by parameters, of generalised Paley graphs with automorphism groups larger than the one-dimensional affine subgroups used to define them. They also shed light on the structure of primitive cyclotomic association schemes.
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Ananchuen, W.: On the adjacency properties of generalized Paley graphs. Australas. J. Combin. 24, 129–147 (2001)
Brouwer, A.E., Cohen, A.M., Neumaier A.: Additions and Corrections to the book Distance-Regular Graphs (Chapter 2). Available at: http://www.win.tue.nl/~aeb/drg/ch2
Brouwer, A.E., Cohen, A.M., Neumaier, A.: Distance-Regular Graphs. In: Ergebnisse der Mathematik und ihrer Grenzgebiete (3), Vol. 18. Springer-Verlag, Berlin (1989)
Brouwer, A.E., Haemers, W.H.: Structure and uniqueness of the $(81,20,1,6)$ strongly regular graph. Discrete Math. 106/107, 77–82 (1992)
Elsawy, A.N.: Paley graphs and their generalizations. arXiv:1203.1818v1 (2012)
Ghinelli, D., Key, J.D.: Codes from incidence matrices and line graphs of Paley graphs. Adv. Math. Commun. 5(1), 93–108 (2011)
Hammack, R., Imrich, W., Klavžar, S.: Handbook of Product Graphs. Second Edition. Discrete Math. Appl. (Boca Raton). CRC Press, Boca Raton, FL (2011)
Jones, G.A.: Paley and the Paley graphs. arXiv:1702.00285 (2017)
Jones, G.A., Wolfart, J.: Dessins d’Enfants on Riemann Surfaces. Springer Monographs in Mathematics. . Springer, Cham (2016)
Key, J.D., Limbupasiriporn, J.: Partial permutation decoding for codes from Paley graphs. Congr. Numer. 170, 143–155 (2004)
Lim, T.K., Praeger, C.E.: On generalised Paley graphs and their automorphism groups. Michigan Math. J. 58(1), 294–308 (2009)
Luo, H., Su, W., Li, Z.: The properties of self-complementary graphs and new lower bounds for diagonal Ramsey numbers. Australas. J. Combin. 25, 103–116 (2002)
Luo, H., Su, W., Shen, Y.-Q.: New lower bounds for two multicolor classical Ramsey numbers. Rad. Mat. 13(1), 15–21 (2004)
Paley, R.E.A.C.: On orthogonal matrices. J. Math. Phys. 12(1-4), 311–320 (1933)
Ponomarenko, I.: Some open problems for coherent configurations. Available at http://www.pdmi.ras.ru/~inp/cp01.pdf (2017)
Sabidussi, G.: Graph multiplication. Math. Z. 72(1), 446–457 (1960)
Schneider, C., Silva, A.C.: Cliques and colorings in generalized Paley graphs and an approach to synchronization. J. Algebra Appl. 14(6), 1550088 (2015)
Seneviratne, P., Limbupasiriporn, J.: Permutation decoding of codes from generalized Paley graphs. Appl. Algebra Engrg. Comm. Comput. 24(3-4), 225–236 (2013)
Su, W., Li, Q., Luo, H., Li, G.: Lower bounds of Ramsey numbers based on cubic residues. Discrete Math. 250(1-3), 197–209 (2002)
van Lint, J.H., Schrijver, A.: Construction of strongly regular graphs, two-weight codes and partial geometries by finite fields. Combinatorica 1(1), 63–73 (1981)
Vizing, V.G.: The Cartesian product of graphs. Vyčisl. Sistemy 9, 30–43 (1963)
Wu, K., Su, W., Luo, H., Li, Z., He, J.: The parallel algorithm for new lower bounds of Ramsey number $R(3, 28)$. (In Chinese) Appl. Res. Comput. 21(9), 40–41 (2004)
Wu, K., Su, W., Luo, H., Xu, X.: A generalization of generalized Paley graphs and new lower bounds for $R(3, q)$. Electron. J. Combin. 17(1), #N25 (2010)
Acknowledgements
We are grateful to Gareth Jones for helpful discussions about the origin of the name Paley graphs. We are also grateful for the nudge he gave us to write up our work for publication. The beginnings of this investigation go back to an undergraduate research project of G. Pearce. In addition the authors are grateful for the thoughtful and helpful comments of anonymous referees which improved the exposition, and also led to a strengthening of Lemma 3.3.
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Pearce, G., Praeger, C.E. Generalised Paley Graphs with a Product Structure. Ann. Comb. 23, 171–182 (2019). https://doi.org/10.1007/s00026-019-00423-0
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DOI: https://doi.org/10.1007/s00026-019-00423-0