Previous |  Up |  Next

Article

Keywords:
arc-transitive graph; symmetric graph; $s$-regular graph
Summary:
A graph is said to be symmetric if its automorphism group acts transitively on its arcs. In this paper, all connected valency seven symmetric graphs of order $2pq$ are classified, where $p$, $q$ are distinct primes. It follows from the classification that there is a unique connected valency seven symmetric graph of order $4p$, and that for odd primes $p$ and $q$, there is an infinite family of connected valency seven one-regular graphs of order $2pq$ with solvable automorphism groups, and there are four sporadic ones with nonsolvable automorphism groups, which is $1,2,3$-arc transitive, respectively. In particular, one of the four sporadic ones is primitive, and the other two of the four sporadic ones are bi-primitive.
References:
[1] Bosma, W., Cannon, J., Playoust, C.: The Magma algebra system. I. The user language. J. Symb. Comput. 24 (1997), 235-265. DOI 10.1006/jsco.1996.0125 | MR 1484478 | Zbl 0898.68039
[2] Cheng, Y., Oxley, J.: On weakly symmetric graphs of order twice a prime. J. Comb. Theory, Ser. B 42 (1987), 196-211. DOI 10.1016/0095-8956(87)90040-2 | MR 0884254 | Zbl 0583.05032
[3] Conway, J. H., Curtis, R. T., Norton, S. P., Parker, R. A., Wilson, R. A.: Atlas of Finite Groups. Maximal Subgroups and Ordinary Characters for Simple Groups. Oxford University Press, Eynsham (1985). MR 0827219 | Zbl 0568.20001
[4] Djoković, D. Ž., Miller, G. L.: Regular groups of automorphisms of cubic graphs. J. Comb. Theory, Ser. B 29 (1980), 195-230. DOI 10.1016/0095-8956(80)90081-7 | MR 0586434 | Zbl 0385.05040
[5] Fang, X. G., Praeger, C. E.: Finite two-arc transitive graphs admitting a Suzuki simple group. Commun. Algebra 27 (1999), 3727-3754. DOI 10.1080/00927879908826659 | MR 1699629 | Zbl 0956.05049
[6] Fang, X., Wang, J., Xu, M. Y.: On 1-arc-regular graphs. Eur. J. Comb. 23 (2002), 785-791. DOI 10.1006/eujc.2002.0579 | MR 1928997 | Zbl 1014.05033
[7] Feng, Y.-Q., Ghasemi, M., Yang, D.-W.: Cubic symmetric graphs of order $8p^3$. Discrete Math. 318 (2014), 62-70. DOI 10.1016/j.disc.2013.11.013 | MR 3141628 | Zbl 1281.05075
[8] Feng, Y.-Q., Kwak, J. H.: Cubic symmetric graphs of order a small number times a prime or a prime square. J. Comb. Theory, Ser. B 97 (2007), 627-646. DOI 10.1016/j.jctb.2006.11.001 | MR 2325802 | Zbl 1118.05043
[9] Feng, Y.-Q., Kwak, J. H., Xu, M.-Y.: Cubic $s$-regular graphs of order $2p^3$. J. Graph Theory 52 (2006), 341-352. DOI 10.1002/jgt.20169 | MR 2242833 | Zbl 1100.05073
[10] Feng, Y.-Q., Li, Y.-T.: One-regular graphs of square-free order of prime valency. Eur. J. Comb. 32 (2011), 265-275. DOI 10.1016/j.ejc.2010.10.002 | MR 2738546 | Zbl 1229.05114
[11] Gardiner, A., Praeger, C. E.: On 4-valent symmetric graphs. Eur. J. Comb. 15 (1994), 375-381. DOI 10.1006/eujc.1994.1041 | MR 1279075 | Zbl 0806.05037
[12] Gardiner, A., Praeger, C. E.: A characterization of certain families of 4-valent symmetric graphs. Eur. J. Comb. 15 (1994), 383-397. DOI 10.1006/eujc.1994.1042 | MR 1279076 | Zbl 0806.05038
[13] Gorenstein, D.: Finite Simple Groups. An Introduction to Their Classification. The University Series in Mathematics, Plenum Press, New York (1982). DOI 10.1007/978-1-4684-8497-7 | MR 0698782 | Zbl 0483.20008
[14] Guo, S.-T., Feng, Y.-Q.: A note on pentavalent $s$-transitive graphs. Discrete Math. 312 (2012), 2214-2216. DOI 10.1016/j.disc.2012.04.015 | MR 2926093 | Zbl 1246.05105
[15] Guo, S., Li, Y., Hua, X.: $(G,s)$-transitive graphs of valency 7. Algebra Colloq. 23 (2016), 493-500. DOI 10.1142/S100538671600047X | MR 3514538 | Zbl 1345.05044
[16] Guo, S.-T., Shi, J., Zhang, Z.-J.: Heptavalent symmetric graphs of order $4p$. South Asian J. Math. 1 (2011), 131-136. MR 3974117 | Zbl 1242.05119
[17] Hua, X.-H., Feng, Y.-Q., Lee, J.: Pentavalent symmetric graphs of order $2pq$. Discrete Math. 311 (2011), 2259-2267. DOI 10.1016/j.disc.2011.07.007 | MR 2825671 | Zbl 1246.05072
[18] Li, Y., Feng, Y.-Q.: Pentavalent one-regular graphs of square-free order. Algebra Colloq. 17 (2010), 515-524. DOI 10.1142/S1005386710000490 | MR 2660442 | Zbl 1221.05201
[19] Liebeck, M. W., Praeger, C. E., Saxl, J.: A classification of the maximal subgroups of the finite alternating and symmetric groups. J. Algebra 111 (1987), 365-383. DOI 10.1016/0021-8693(87)90223-7 | MR 0916173 | Zbl 0632.20011
[20] Lorimer, P.: Vertex-transitive graphs: symmetric graphs of prime valency. J. Graph Theory 8 (1984), 55-68. DOI 10.1002/jgt.3190080107 | MR 0732018 | Zbl 0535.05031
[21] McKay, B. D.: Transitive graphs with fewer than twenty vertices. Math. Comput. 33 (1979), 1101-1121. DOI 10.2307/2006085 | MR 0528064 | Zbl 0411.05046
[22] Miller, R. C.: The trivalent symmetric graphs of girth at most six. J. Comb. Theory, Ser. B 10 (1971), 163-182. DOI 10.1016/0095-8956(71)90075-X | MR 0285435 | Zbl 0223.05113
[23] Oh, J.-M.: A classification of cubic $s$-regular graphs of order $14p$. Discrete Math. 309 (2009), 2721-2726. DOI 10.1016/j.disc.2008.06.025 | MR 2523779 | Zbl 1208.05055
[24] Oh, J.-M.: A classification of cubic $s$-regular graphs of order $16p$. Discrete Math. 309 (2009), 3150-3155. DOI 10.1016/j.disc.2008.09.001 | MR 2526732 | Zbl 1177.05052
[25] Pan, J., Ling, B., Ding, S.: One prime-valent symmetric graphs of square-free order. Ars Math. Contemp. 15 (2018), 53-65. DOI 10.26493/1855-3974.1161.3b9 | MR 3862077
[26] Pan, J., Lou, B., Liu, C.: Arc-transitive pentavalent graphs of order $4pq$. Electron. J. Comb. 20 (2013), Researh Paper P36, 9 pages. MR 3035046 | Zbl 1266.05061
[27] Potočnik, P.: A list of 4-valent 2-arc-transitive graphs and finite faithful amalgams of index $(4,2)$. Eur. J. Comb. 30 (2009), 1323-1336. DOI 10.1016/j.ejc.2008.10.001 | MR 2514656 | Zbl 1208.05056
[28] Sabidussi, G.: Vertex-transitive graphs. Monatsh. Math. 68 (1964), 426-438. DOI 10.1007/BF01304186 | MR 0175815 | Zbl 0136.44608
[29] Sims, C. C.: Graphs and finite permutation groups. Math. Z. 95 (1967), 76-86. DOI 10.1007/BF01117534 | MR 0204509 | Zbl 0244.20001
[30] Suzuki, M.: Group Theory I. Grundlehren der Mathematischen Wissenschaften 247, Springer, Berlin (1982). DOI 10.1007/978-3-642-61804-8 | MR 0648772 | Zbl 0472.20001
[31] Wilson, R. A.: The Finite Simple Groups. Graduate Texts in Mathematics 251, Springer, London (2009). DOI 10.1007/978-1-84800-988-2 | MR 2562037 | Zbl 1203.20012
[32] Xu, J., Xu, M.: Arc-transitive Cayley graphs of valency at most four on abelian groups. Southeast Asian Bull. Math. 25 (2001), 355-363. DOI 10.1007/s10012-001-0355-z | MR 1935107 | Zbl 0993.05086
[33] Xu, M.-Y.: Automorphism groups and isomorphisms of Cayley digraphs. Discrete Math. 182 (1998), 309-319. DOI 10.1016/S0012-365X(97)00152-0 | MR 1603719 | Zbl 0887.05025
[34] Zhou, J.-X., Feng, Y.-Q.: Tetravalent $s$-transitive graphs of order twice a prime power. J. Aust. Math. Soc. 88 (2010), 277-288. DOI 10.1017/S1446788710000066 | MR 2629936 | Zbl 1214.05052
Partner of
EuDML logo