The L(2,1) -Labeling of Outerplane Graphs
Xinhong Wang · Journal of Mathematical Research and Exposition · 2003
It is proved that an outerplane graph contains no subdivision of K4 or K2,3 . Let G be an outerplane graph. We show that the L(2,1) -labeling number λ(G)≤△(G) + 9 , where △(G) is the maximum degree of vertices in G .