Binary operation/Commutative/Definition

Commutative operation

A binary operation

$\circ \colon M\times M\longrightarrow M,(x,y)\longmapsto x\circ y,$

on a set ${}M$ is called commutative, if for all ${}x,y\in M$ the equality

${}x\circ y=y\circ x\,$

holds.