A classification result about basic 2-arc-transitive graphs

Abstract

A connected graph Γ=(V,E) is called a basic 2-arc-transitive graph if its full automorphism group has a 2-arc-transitive subgroup G, and every minimal normal subgroup of G has at most two orbits on V. In 1993, Praeger proved that every finite 2-arc-transitive connected graph is a cover of some basic 2-arc-transitive graph, and proposed the classification problem of finite basic 2-arc-transitive graphs. In this paper, a classification is given for basic 2-arc-transitive non-bipartite graphs of order rasb and basic 2-arc-transitive bipartite graphs of order 2rasb, where r and s are distinct primes.