Definition:Disjoint Union (Set Theory)/Also known as

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Disjoint Union: Also known as

A disjoint union in the context of set theory is also called a discriminated union.

In Georg Cantor's original words:

We denote the uniting of many aggregates $M, N, P, \ldots$, which have no common elements, into a single aggregate by
$\tuple {M, N, P, \ldots}$.
The elements in this aggregate are, therefore, the elements of $M$, of $N$, of $P$, $\ldots$, taken together.