IfG =(e)with v= n ande =o, then G consists of n isolated points and by the product rule pg(h)=k IfG =Kn, the complete graph on n vertices, then at least n colors must be available for a proper coloring of G. Here by the product rue Pc()=k(k-1)(k-2)、k-n+1). We see that for k n, PG(k)=0, which indicates there is no proper k-coloring of Kn▪ If G = (V, E ) with |V | = n and E =, then G consists of n isolated points, and by the product rule PG(k ) = k n . ▪ If G =Kn , the complete graph on n vertices, then at least n colors must be available for a proper coloring of G. Here, by the product rule ▪ P G(k ) = k (k-1)(k-2)...(k-n + 1). ▪ We see that for k < n, P G(k ) = 0, which indicates there is no proper k -coloring of Kn