第二小阶数的双本原半对称图

Biprimitive Semisymmetric Graphs of Second Small Order

如果一个正则图是边传递但不是点传递的,那么我们称它是半对称的.每一个半对称图X必定是两部分点数相等的二部图,并且它的自同构群Aut(X)在每一部分上是传递的.如果一个半对称图的自同构群在每一部分上作用是本原的,那么我们称它是双本原的.本文决定了第二小阶数的双本原半对称图.

A regular edge-transitive graph which is not vertex-transitive is said to be semisymmetric. Every semisymmetric graph X is necessarily bipartite, the two parts having equal size, and the automorphism group Aut（X） acting transitively on each of these parts. A semisymmetric graph is called biprimitive if its automorphism group acts primitively on each part. In this paper biprimitive semisymmetric graphs of second small order are determined.