Description: The strong form of the Axiom of Regularity, which does not require that A be a set. Axiom 6' of TakeutiZaring p. 21. See also epfrs . (Contributed by NM, 17-Sep-2003)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | zfregs | |- ( A =/= (/) -> E. x e. A ( x i^i A ) = (/) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | zfregfr | |- _E Fr A |
|
| 2 | epfrs | |- ( ( _E Fr A /\ A =/= (/) ) -> E. x e. A ( x i^i A ) = (/) ) |
|
| 3 | 1 2 | mpan | |- ( A =/= (/) -> E. x e. A ( x i^i A ) = (/) ) |