On vertex types of graphs

Abstract

The vertices of a graph are classified into seven types by J.T. Hedetniemi, S.M. Hedetniemi, S.T. Hedetniemi and T.M. Lewis and they ask the following questions: 1) What is the smallest order $n$ of a graph having $n-2$ very typical vertices or $n-2$ typical vertices? 2) What is the smallest order of a pantypical graph? We answer these two questions in this paper.