In simple terms, let ,
, and
be members of an algebra. Then
the algebra is said to be associative if
(1)
|
where
denotes multiplication. More formally, let
denote an
-algebra, so that
is a vector space over
and
(2)
|
(3)
|
Then
is said to be
-associative
if there exists an
-dimensional
subspace
of
such that
(4)
|
for all
and
.
Here, vector multiplication
is assumed to be bilinear.
An
-dimensional
-associative
algebra is simply said to be "associative."