1.NounA subset of the Cartesian product
A
×
A
{\displaystyle A\times A}
(the set of ordered pairs (
a
{\displaystyle a}
,
b
{\displaystyle b}
) of elements of
A
{\displaystyle A}
, alternatively written as
A
2
{\displaystyle A^{2}}
).
2.NounA subset of the Cartesian product
A
×
B
{\displaystyle A\times B}
.