Disjoint union
In set theory, a disjoint union is a type of union (Set theoretic union), in which each element of the union is disjoint from the others: intersection with every other element of the union is the empty set.
i.e. Suppose C is a collection of sets, then:
is a disjoint union if and only if
See also: Basic Set Theory
\mathcal{A} = \bigcup_{A \in C} A
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\forall A,B \in C \quad
st. \ A \ne B: A \cap B = \empty
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