Definition:Non-Empty Set/Class Theory

Theorem

Let $A$ be a class.

Then $A$ is non-empty if and only if $A$ has at least one element.

Also known as

Some sources prefer to use nonempty, but $\mathsf{Pr} \infty \mathsf{fWiki}$, in striving for consistency, standardises on non-empty.

Also see

• Definition:Non-Empty Set
• Definition:Empty Set

• Definition:Empty Class (Class Theory)