The cordiality of one-point union of \(n\) copies of a graph
This paper gives a contribution on vertex labelings---the so-called cordial labellings---of graphs. The two authors succeed in determining interesting classes of cordial graphs defined as amalgamation of \(n\) copies of a graph. It is remarkable that they are able to develop a theory of cordial graphs by applying results, methods and facts of the theory of solution of equations and inequalities. So they can prove some necessary and sufficient conditions for the cordiality of their special classes of graphs. It remains open whether it is possible to generalize this method in an appropriate way to find a theory of determining the set of all cordial graphs. This paper can be considered as an encouragement for continuing research on cordial graphs.
scientific article; zbMATH DE number 428010