Small collection

The precise meaning of small depends on the choice of foundation being used.

In $Z F C$ and its conservative extensions (e.g. $N B G$ ), the term merely emphasizes that a set is not a proper class.
In foundations with universes such as $T G$ , a set $𝑥$ is small with respect to a universe $𝑈$ if $𝑥 \in 𝑈$ .

#state/tidy | #lang/en | #SemBr