20.500.12556/RUL-170481 Normal covers of 2-arc-transitive graphs of prime-power order In a paper by Cai Heng Li in Bull. London Math. Soc. 33 (2001), it was suggested that ‘non-basic’ $2$-arc-transitive graphs of prime-power order that occur as normal covers of smaller $2$-arc-transitive graphs might be rare and difficult to construct. This note describes some of the background to Li’s suggestion, and gives some examples of small valency, and then goes on to show that in fact there are infinitely many examples of valency $d$, for every integer $d \ge 2$. It is also noted that the hypercubes $(Q_n)$ for $n \ge 4$ even, together with a $2$-arc-transitive group $G$ of index $2$ in ${\rm Aut}(Q_n)$, show that the claims of Corollary 1.2 in the above paper by Li are not quite correct. graphs s-arc-transitive normal cover true false true Angleški jezik Angleški jezik Članek v reviji 2025-07-07 10:57:02 2025-07-07 10:57:04 2025-07-08 04:20:21 0000-00-00 00:00:00 2025 0 0 Str. 469-478 iss. 2 Vol. 8 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2025-01-01 519.17 2589-5486 10.5802/alco.415 241575683 ALCO_2025__8_2_469_0.pdf ALCO_2025__8_2_469_0.pdf 1 ACBD8E99E312B628B4F795AA508CD83E 419e37bbb13136340c200fbf8e0463ec4af72130132937b487c099a048a793a0 42830941-5b0f-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=212489 https://alco.centre-mersenne.org/articles/10.5802/alco.415/ 1 726b8eec-5b0e-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=212488 Fakulteta za matematiko in fiziko 0 0 0