Cartesian product of a set by itself.
Example
Consider the set A = {a, b, c}, then A × A = A² = {(a, a), (a, b), (a,c), (b, a), (b, b), (b, c), (c, a), (c, b), (c, c)} is the Cartesian square in A.
We can represent a Cartesian square of a set with a table, such as a multiplication table, or an arrow diagram :
