Counting Graph Homomorphisms Involving Complete Graphs

Abstract

In the branch of mathematics known as graph theory, graphs are considered as a set of points, called vertices, with connections between these points, called edges. The purpose of this paper is to study mappings between two graphs that have certain desirable properties, called graph homomorphisms, and the probability of such a mapping occurring. By using notions from graph theory and combinatorics, in this paper we prove several new theorems that place bounds on this probability for certain common classes of graphs such as Kn, and show that isolated vertices may safely be ignored.