Volume 21 • Number 2 • 1998   • On Digraphs with Non-derogatory Adjacency Matrix C.L. Deng and C.S. Gan Abstract. Let G be a digraph with n vertices and A(G) be its adjacency matrix. A monic polynomial f(x) of degree at most n is called an annihilating polynomial of G if f ( A(G)) = 0. G is said to be annihilatingly unique if it possesses a unique annihilating polynomial. We prove that two families of digraphs, i.e., the ladder digraphs and the difans, are annihilatingly unique by studying the similarity invariants of their adjacency matrices respectively. Full text: PDF