3 ms·
There is no U in ZF so I really don't understand what you are saying.
by defen 11y ago
There is no U in ZF so I really don't understand what you are saying.
- Shaniqua 11y agoYou can call U anything you want. It's by axiom schema of specification: for any set A, there some set B with a set C in B iff C in A.