New Results on Difference Distance Magic Labelings

TL;DR

This paper investigates difference distance magic labelings in oriented graphs, establishing existence results for all sizes above 4, introducing a new graph sum construction, and linking the concept to linear algebra.

Contribution

It proves the existence of connected difference distance magic oriented graphs for all n ≥ 5 and introduces a novel graph sum method along with a linear algebra connection.

Findings

Existence of such graphs for all n ≥ 5.

A new graph sum construction method.

Connection between linear algebra and difference distance magic labelings.

Abstract

A graph labeling assigns values to the components of a graph (vertices, edges, etc.). In particular, distance magic labelings have been widely studied in undirected graphs. In such a labeling, the vertices are labeled with unique values from one up to the number of vertices so that the sum of labels on the neighbors of any vertex is the same across all vertices. For oriented graphs, a related concept of distance difference magic has been studied. In a distance difference magic labeling, each vertex is given a unique value from one up to the number of vertices such that for each vertex the sums of the labels of vertices in the in-neighborhood minus the sums of the labels of vertices in the out-neighborhood equals zero. In this paper, we expand on this concept by showing a connected difference distance magic oriented graph on $n$ vertices exists for each integer $n \geq 5$. We also construct arbitrarily large difference distance magic oriented graphs from smaller ones using a new graph sum and exhibit a connection between linear algebra and this type of labeling.