Disjoint union

Common card · No. 328247

In mathematics, the disjoint union (or discriminated union) A ⊔ B {\displaystyle A\sqcup B} of the sets A and B is the set formed from the elements of A and B labelled (indexed) with the name of the set from which they come. So, an element belonging to both A and B appears twice in the disjoint union, with two different labels. A disjoint union of an indexed family of sets ( A i : i ∈ I ) {\displaystyle (A_{i}:i\in I)} is a set A , {\displaystyle A,} often denoted by ⨆ i ∈ I A i , {\textstyle \bigsqcup _{i\in I}A_{i},} with an injection of each...

Read on Wikipedia · Image Kismalac, CC BY-SA 3.0