The purpose of this paper is studying some properties of clean,
semi-clean and quasi-clean rings, and study the relationship between
these rings. A ring is called clean if each of its element is the sum of
an idempotent and a unit, a ring is calle
d semi-clean if each of its
element is the sum of an idempotent and a regular, a ring is called
quasi-clean if each of its element is the sum of an idempotent and an
pi .
