Bounds on the Edge Magic Number for Complete Graphs

Addie Armstrong1, Jacob Smith2
1Department of Mathematics, Norwich University, Northfield VT
2Department of Mathematics, University of Rhode Island, Kingston RI 02881

Abstract

An edge-magic total labeling of a graph \(G = (V, E)\) is an assignment of integers \(1,2, …,|V|+|E|\) to the vertices and edges of the graph so that the sum of the labels of any edge \(uv\) and the labels on vertices \(u\) and \(v\) is constant. It is known that the class of complete graphs on \(n\) vertices, \(K_n\), are not edge magic for any n ≥ 7. The edge magic number \(M_E(K_n)\) is defined to be the minimum number t of isolated vertices such that \(K_n \cup tK_1\), is edge magic. In this paper we show that, for n ≥ 10, \(M_E(K_n) ≤ f_{n+1} + 57 – \frac{n^2+n}{2} where \(f_i\) is the \(i^{th}\) Fibonacci number. With the aid of a computer, we also show that \(M_E(K_7) = 4,\, M_E(K_8) = 10\), and \(M_E(K_9) = 19\), answering several questions posed by W. D. Wallis.