Description: Equivalent formulas yield equal restricted class abstractions (inference form). (Contributed by NM, 22-May-1999) (Proof shortened by Wolf Lammen, 12-Jan-2025)
Ref | Expression | ||
---|---|---|---|
Hypothesis | rabbiia.1 | |- ( x e. A -> ( ph <-> ps ) ) |
|
Assertion | rabbiia | |- { x e. A | ph } = { x e. A | ps } |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | rabbiia.1 | |- ( x e. A -> ( ph <-> ps ) ) |
|
2 | 1 | pm5.32i | |- ( ( x e. A /\ ph ) <-> ( x e. A /\ ps ) ) |
3 | 2 | rabbia2 | |- { x e. A | ph } = { x e. A | ps } |