# Metamath Proof Explorer

## Table of Contents - 20.16.5.16. Set theory: elementary operations relative to a universe

Some elementary set-theoretic operations "relative to a universe" (by which
is merely meant some given class considered as a universe).

- bj-rcleqf

- bj-rcleq

- bj-reabeq

- bj-disj2r

- bj-sscon