International Journal of Mathematics and Mathematical Sciences 
Volume 2007 (2007), Article ID 46851, 8 pages
doi:10.1155/2007/46851
Research Article

Nonderogatory Unicyclic Digraphs

Diego Bravo and Juan Rada

 Departamento de Matemáticas, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101, Venezuela
Received 6 October 2006; Accepted 9 February 2007

Recommended by Dalibor Froncek

Abstract

A digraph is nonderogatory if its characteristic polynomial and minimal polynomial are equal. We find a characterization of nonderogatory unicyclic digraphs in terms of Hamiltonicity conditions. An immediate consequence of this characterization ia that the complete product of difans and diwheels is nonderogatory.