Definition:Cayley-Dickson Construction

Definition

Let $A = \left({A_F, \oplus}\right)$ be a $*$-algebra.

The Cayley-Dickson Construction on $A$ is the procedure which generates a new algebra $A'$ from $A$ as follows.

Let:

$A' = \left({A'_F, \oplus'}\right) = \left({A, \oplus}\right)^2$

where $\left({A, \oplus}\right)^2$ denotes the Cartesian product of $\left({A, \oplus}\right)$ with itself.

Then $\oplus'$ and $*'$ are defined on $A'$ as follows:

$\left({a, b}\right) \oplus' \left({c, d}\right) = \left({a \oplus c - d \oplus b^*, a^* \oplus d + c \oplus b}\right)$

${\left({a, b}\right)^*}' = \left({a^*, -b}\right)$

where:

$\left({a, b}\right), \left({c, d}\right) \in A'$

$a^*$ is the conjugation of $a \in A$.

If $\dim \left({A_F}\right)$ is $d$, then $\dim \left({A'_F}\right)$ is $2 d$.

Also see

• Cayley-Dickson Construction forms a $*$-Algebra

• Results about the Cayley-Dickson construction can be found here.

Source of Name

This entry was named for Arthur Cayley and Leonard Eugene Dickson.

Sources

• John C. Baez: The Octonions (2002): 2.2 The Cayley-Dickson Construction