The disjoint union of two sets A and B is a binary operator that combines all distinct elements of a pair of given sets, while retaining the original set membership as a distinguishing characteristic of the union set. The disjoint union is denoted A union ^* B = (A×{0}) union (B×{1}) congruent A^* union B^*, where A×S is a Cartesian product.

graph union | union | unsorted union