Valency seven symmetric graphs of order $2pq$
Czechoslovak Mathematical Journal, Tome 68 (2018) no. 3, pp. 581-599
Cet article a éte moissonné depuis la source Czech Digital Mathematics Library
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.
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.
DOI :
10.21136/CMJ.2018.0530-15
Classification :
05C25, 20B25
Keywords: arc-transitive graph; symmetric graph; $s$-regular graph
Keywords: arc-transitive graph; symmetric graph; $s$-regular graph
@article{10_21136_CMJ_2018_0530_15,
author = {Hua, Xiao-Hui and Chen, Li},
title = {Valency seven symmetric graphs of order $2pq$},
journal = {Czechoslovak Mathematical Journal},
pages = {581--599},
year = {2018},
volume = {68},
number = {3},
doi = {10.21136/CMJ.2018.0530-15},
mrnumber = {3851877},
zbl = {06986958},
language = {en},
url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.2018.0530-15/}
}
TY - JOUR AU - Hua, Xiao-Hui AU - Chen, Li TI - Valency seven symmetric graphs of order $2pq$ JO - Czechoslovak Mathematical Journal PY - 2018 SP - 581 EP - 599 VL - 68 IS - 3 UR - http://geodesic.mathdoc.fr/articles/10.21136/CMJ.2018.0530-15/ DO - 10.21136/CMJ.2018.0530-15 LA - en ID - 10_21136_CMJ_2018_0530_15 ER -
Hua, Xiao-Hui; Chen, Li. Valency seven symmetric graphs of order $2pq$. Czechoslovak Mathematical Journal, Tome 68 (2018) no. 3, pp. 581-599. doi: 10.21136/CMJ.2018.0530-15
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