Chromatic Index Critical Graphs of Odd Order with Five Major Vertices

In an earlier paper [11], we proved that there does not exist any \(\Delta\)-critical graph of even order with five major vertices. In this paper, we prove that if \(G\) is a \(\Delta\)-critical graph of odd order \(2n+1\) with five major vertices, then \(e(G) = n\Delta+1\). This extends an earlier result of Chetwynd and Hilton, and also completes our characterization of graphs with five major vertices. In [9], we shall apply this result to establish some results on class 2 graphs whose core has maximum degree two.