A clique in a graph G is a complete subgraph of G. A clique covering (partition) of G is a collection C of cliques such that each edge of G occurs in at least (exactly) one clique in C. The clique covering (partition) number cc(G) (cp(G)) of G is the minimum size of a clique covering (partition) of G. This paper gives alternative proofs, using a unified approach, for the results on the clique covering (partition) numbers of line graphs obtained by McGuinness and Rees [11]. We also employ the proof techniques to give an alternative proof for the De Brujin-Erdos Theorem. Keywords. Clique, covering, partition, line graph, semiwing, wing, 3-wing.
Bo-Jr Li, Gerard J. Chang