Published online by Cambridge University Press: 13 May 2015
Let $X$ be a simple, connected,
$p$-valent,
$G$-arc-transitive graph, where the subgroup
$G\leq \text{Aut}(X)$ is solvable and
$p\geq 3$ is a prime. We prove that
$X$ is a regular cover over one of the three possible types of graphs with semi-edges. This enables short proofs of the facts that
$G$ is at most 3-arc-transitive on
$X$ and that its edge kernel is trivial. For pentavalent graphs, two further applications are given: all
$G$-basic pentavalent graphs admitting a solvable arc-transitive group are constructed and an example of a non-Cayley graph of this kind is presented.