A graph is said to be 1 2 -transitive if its automorphism group acts transitively on vertices and edges but not on arcs. For each n 11, a 1 2 -transitive graph of valency 4 and girth 6, with the automorphism group isomorphic to A n \_Z 2 , is given.
SGDs with doubly transitive automorphism group
β Scribed by Cameron, Peter J.
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 168 KB
- Volume
- 32
- Category
- Article
- ISSN
- 0364-9024
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β¦ Synopsis
Symmetric graph designs, or SGDs, were defined by Gronau et al. as a common generalization of symmetric BIBDs and orthogonal double covers. This note gives a classification of SGDs admitting a 2-transitive automorphism group. There are too many for a complete determination, but in some special cases the determination can be completed, such as those that admit a 3-transitive group, and those with Ξ» = 1. The latter case includes the determination of all near 1factorizations of K n (partitions of the edge set into subsets each of which consists of disjoint edges covering all but one point), which admit 2-transitive groups.
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