NIL CLEAN INDEX OF RINGS

Abstract

Motivated by the concept of clean index of rings of Lee and Zhou we introduce the concept of nil clean index of rings. For any element a of a ring R with unity, we define η(a) = {e ∈ R | e 2 = e and a−e ∈ nil(R)}, where nil(R) is the set of all nilpotent elements of R. Then nil clean index of R is defined by sup{ |η(a)| : a ∈ R} and it is denoted by Nin(R). In this article, we characterize rings of nil clean indices 1, 2 and 3 and prove some interesting results pertaining them.