The set of values or objects that can be used as the first components of the ordered pairs of a relation.
This is not to be confused with the domain of a relation, which is the set of the first components of the ordered pairs of a relation. Therefore, given a relation ℜ from E to F, dom(ℜ) ⊆ E, that is, the domain of the relation is a large subset of the set of departure.
Examples
- In this illustration of a relation between the set E and the set F, the set E = {2, 3, 4, 5} is the set of departure of the relation. The domain of this relation is {2, 4}.
- Consider the relation y = 2x+ 1, where x is a natural number.
The set of departure is the set of whole numbers: {0, 1, 2, 3, 4, …}
The set of destination is the set of odd whole numbers: {1, 3, 5, 7, 9, …}