In mathematics, more specifically abstract algebra and ring theory, a noncommutative ring is a ring whose multiplication is not required to be commutative; that is, there may exist a and b in R with a·b ≠ b·a. These include commutative rings as a subclass. Noncommutative algebra is the study of results applying to rings that are not required to be commutative. Many important results in the field of noncommutative algebra apply to commutative rings as special cases. Some authors use the term noncommutative ring to refer to a ring that is strictly noncommutative, that is, for which there do exist a and b in R with a·b ≠ b·a.
|Algebraic structure → Ring theory|
Although some authors do not assume that rings have a multiplicative identity, in this article we make that assumption unless stated otherwise.