Edited sentence: Another remarkable theorem by Joseph Wedderburn, known as Wedderburn's little theorem, asserts that any finite division ring is necessarily commutative.If for every element r of R there exists an integer  such that , then R is commutative.If, r2 = r for every r, the ring is called a Boolean ring.More general conditions which guarantee commutativity of a ring are also known.Nathan Jacobson later discovered yet another condition which guarantee's commutativity of a ring: