A CHARACTERIZATION OF GROUP-DIVISIBLE DESIGNS AND SOME RELATED RESULTS

摘要

The main purpose of this paper is to show that these designs are group-divisible. The whole problem will be formulated and solved in the context of graph theory.nA regular graph G is a graph with no multiple edges and loops (i.e., there is at most one edge connecting two different vertices and any vertex is not joined with itself) such that each of its vertices is adjacent (or connected) to the same number of other vertices. This number is called the degree of 6.