Description: An inference based on the Axiom of Replacement. Typically, ph defines a function from x to y . (Contributed by NM, 26-Nov-1995)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | zfrep3cl.1 | |- A e. _V | |
| zfrep3cl.2 | |- ( x e. A -> E. z A. y ( ph -> y = z ) ) | ||
| Assertion | zfrep3cl | |- E. z A. y ( y e. z <-> E. x ( x e. A /\ ph ) ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | zfrep3cl.1 | |- A e. _V | |
| 2 | zfrep3cl.2 | |- ( x e. A -> E. z A. y ( ph -> y = z ) ) | |
| 3 | nfcv | |- F/_ x A | |
| 4 | 3 1 2 | zfrepclf | |- E. z A. y ( y e. z <-> E. x ( x e. A /\ ph ) ) |