Definition:Unordered Tuple

Definition
An Unordered Tuple is a small class in ZF set theory that contains a finite number of elements.

It is written using roster notation and is denoted $\left\{ a_1, a_2 , \dots a_n \right\}$


 * $\left\{ a_1, a_2 , \dots a_n \right\} = \left\{ x : x = a_1 \lor x = a_2 \lor \dots x = a_n \right\}$