disjoint union

Noun

 * 1)  A union of sets forced to be disjoint by attaching information referring to the original sets to their elements (i.e., by using indexing).
 * 2)  A union of sets which are already pairwise disjoint.
 * 3)  The disjoint union of the underlying sets of a given family of topological spaces, equipped with a topology.

Usage notes
The two senses defining unions of sets are rarely distinguished with much care, except in a very formal setting. In category theory, they are essentially identical: both are realisations of the coproduct of a category of sets.

Translations

 * Italian: unione disgiunta
 * Swedish:


 * Italian: unione disgiunta
 * Swedish:


 * Icelandic: sundurlæga sammengi