L(2,1)-labelling number of 2-outer planar graphs
Weifan Wang · Journal of Zhejiang Normal University · 2009
A kind of 2-outer planar graph G which was defined as a planar graph possessed a plane embedding with its vertex set contained in a boundary of at most two faces was studied.An L(2,1)-labelling case was discussed: For a 2-outer planar graph,there holded λ(G)≤Δ(G)+12,where Δ(G) denoted the maximun degree of graph G.