A clique in an undirected graph G = (V, E) is a subset of V i.e. V’ such that each pair of vertices in V’
is connected by an edge. A clique of size k is called k- clique. A 0- clique contains set of 0 vertices.
A maximal clique is a clique that cannot be extended by including one more adjacent vertex. A
maximum clique of G is such that there is no clique with more vertices.