Quasipolar Subrings of 3 X 3 Matrix Rings

Abstract

An element a of a ring R is called quasipolar provided that there exists an idempotent p is an element of R such that p is an element of comm(2)(a), a + p is an element of U(R) and ap is an element of R-qnil. A ring R is quasipolar in case every element in R is quasipolar. In this paper, we determine conditions under which subrings of 3 x 3 matrix rings over local rings are quasipolar. Namely, if R is a bleached local ring, then we prove that J(3)(R) is quasipolar if and only if R is uniquely bleached. Furthermore, it is shown that T-n(R) is quasipolar if and only if T-n(R[[x]]) is quasipolar for any positive integer n.