Description: Alternate definition of restricted class abstraction. (Contributed by NM, 20-Sep-2003) (Proof shortened by BJ, 22-Apr-2019)
Ref | Expression | ||
---|---|---|---|
Assertion | dfrab2 | |- { x e. A | ph } = ( { x | ph } i^i A ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfrab3 | |- { x e. A | ph } = ( A i^i { x | ph } ) |
|
2 | incom | |- ( A i^i { x | ph } ) = ( { x | ph } i^i A ) |
|
3 | 1 2 | eqtri | |- { x e. A | ph } = ( { x | ph } i^i A ) |