The definition of a group does not require that a ⋅ ⋅ b = b ⋅ ⋅ a for all elements a and b in ⁠ G ⁠. If this additional condition holds, then the operation is said to be commutative, and the group is called an abelian group. It is a common convention that for an abelian group either additive or multiplicative notation may be used, but for a nonabelian group only multiplicative notation is used.