Definition:Singleton Relation

Definition

Let $S$ and $T$ be sets.

Let $\RR \subseteq S \times T$ be a relation on $S \times T$.

Then $\RR$ is a singleton relation if and only if:

$\exists_1 \tuple {x, y} \in S \times T: \tuple {x, y} \in \RR$

That is, if and only if $\RR$ has exactly one element.

Also see

• Definition:Singleton