(a) Let G be an undirected graph with n vertices. If G is isomorphic to its own complement , how many edges must G have? (Such a graph is called self-complementary.)
(b) Find an example of a self-complementary graph on four vertices and one on five vertices.
(c) If G is a self-complementary graph on n vertices, where n > 1, prove that n = 4k or n = 4k + 1, for some k ∈ Z+.