Commutativity

Commutativity is the ability to change the order of something without changing the end result.

A binary operation ∗ on a set S is commutative if:

$\forall x,y\in S:x*y=y*x\,$

A binary function f:A×A → B is commutative if:

$\forall x,y\in A:f(x,y)=f(y,x)\,$