Some properties of graphs constructed from 2-designs

摘要

Let D = (P, B) be any nontrivial nonsymmetric 2-(v, k, lambda) design. In this paper we construct a connected, regular and bipartite graph, say IG(v,b) (D), from D. Some graphic properties of IG(v,b) (D) are investigated. In particular, the results in the paper bridges the equivalency between edge-transitivity of IG(v,b) (D) and flag-transitivity of D. With the equivalency, it is obtained that IG(v,b) (D) is a semisymmetric graph as long as D is a nonsymmetric flag-transitive 2-(v, k, lambda) design. (C) 2016 Elsevier Inc. All rights reserved.