On The Boundary Inequality For Bandwidth Of Graphs

Hongxiang Li1, Yixun Lin2
1Research Institute of Applied Mathematics Shanghai Institute of Railway Technology Shanghai 200333, P.R. China
2Department of Mathematics Zhengzhou University Zhengzhou 450052, P.R. China

Abstract

The quantity \(B(G) = \min \max\{|f(u)-f(v)|: (u,v) \in E(G)\}\) is called the bandwidth of a graph \(G = (V(G), E(G))\) where \(\min\) is taken over all bijections \(f: V(G) \to \{1,2,\ldots,|V(G)|\}\) called labelings. L.H. Harper presented an important inequality related to the boundary of subsets \(S \subseteq V(G)\). This paper gives a refinement of Harper’s inequality which will be more powerful in determining bandwidths for several classes of graphs.