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

Let Nn+1 (R) be the algebra of all strictly upper triangular n + I by n + I matrices over a 2-torsionfree commutative local ring R with identity. In this paper, we prove that any Jordan automorphism, of Nn+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 greater than or equal to 3. In the cases it = 1, 2, we also give a decomposition for any Jordan automorphism of Nn+1 (R) (I less than or equal to n less than or equal to 2). (C) 2004 Elsevier Inc. All rights reserved.