Decomposition of Jordan automorphisms of strictly triangular matrix algebra over local rings

Let N_n+1 (R) be the algebra of all strictly upper triangular n + 1 by n + 1 matrices over a 2-torsionfree commutative local ring R with identity. In this paper, we prove that any Jordan automorphism of N _n+1 (R) can be uniquely written as a product of a graph automorphism, a diagonal automorphism, an inner automorphism and a central automorphism for n ≥ 3. In the cases n = 1, 2, we also give a decomposition for any Jordan automorphism of N_n+1 (R) (1 ≤ n ≤ 2).