Finite 2-geodesic transitive graphs of prime valency

Abstract

We classify non-complete prime valency graphs satisfying the property that their automorphism group is transitive on both the set of arcs and the set of $2$-geodesics. We prove that either $\hat{I}“$ is 2-arc transitive or the valency $p$ satisfies $p\equiv 1(\mathrm{mod}4)$, and for each such prime there is a unique graph with this property: it is a non-bipartite antipodal double cover of the complete graph $K_{p+1}$ with automorphism group $PSL(2,p)\times Z_2$ and diameter 3.

arXiv admin note: substantial text overlap with arXiv:1110.2235