# Commutativity

(redirected from*Noncommutative*)

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Related to Noncommutative: Commutative operation

## Commutativity

a property of the addition and multiplication of numbers expressed by the identities *a + b = b* + *a* and *ab = ba*. In a more general sense, the operation *a * b* is termed commutative if *a * b = b* **a*. Addition and multiplication of polynomials, for example, have the property of commutativity; vector multiplication (*see* VECTOR PRODUCT) is not commutative since [a,b] = — [b,a].