(2,3) Cordial Trees and Paths

TL;DR

This paper investigates $(2,3)$-cordial labelings of directed graphs, disproves two conjectures about paths and trees, explores the Petersen graph, and provides bounds and applications for such labelings.

Contribution

It disproves two conjectures on $(2,3)$-cordial labelings of paths and trees, and extends understanding of these labelings to other graphs and applications.

Findings

Conjectures on paths and trees are false.

Provides bounds for $(2,3)$-cordial graphs.

Discusses applications of $(2,3)$-cordial labelings.

Abstract

Recently L. B. Beasley introduced $(2,3)$-cordial labelings of directed graphs in [1]. He made two conjectures which we resolve in this article. He conjectured that every orientation of a path of length at least five is $(2,3)$ cordial, and that every tree of max degree $n =3$ has a cordial orientation. We show these two conjectures to be false. We also discuss the $(2,3)$ cordiality of orientations of the Petersen graph, and establish an upper bound for the number of edges a graph can have and still be $(2,3)$ cordial. An application of $(2,3)$ cordial labelings is also presented.