EDB — 252

[252]Prerequisites:[23T]↺↻,[026]↺↻,[1Y0]↺↻,[00S]↺↻. Let $A$ be a non-empty set; we define $B$ as the set that contains all the elements that are in all the elements of $A$. Write a well-formed formula that defines $B$, prove that $B$ is indeed a set, and show that it is unique; for symmetry with the axiom [026]↺↻ we will indicate it with

It is related to the usual notation by the relation