Efficient domination in circulant graphs

Results about wreath products of circulant graphs are used to construct infinitely many circulant graphs with efficient dominating sets whose elements need not be equally spaced in Z n . It is proved that if a circulant graph of large degree has an efficient dominating set, then either its elements are equally spaced, or the graph is the wreath product of a smaller circulant graph with an efficient dominating set and a complete graph.