theorem abeqd (G: wff) {x: nat} (p q: wff x):
$ G -> (p <-> q) $ >
$ G -> {x | p} == {x | q} $;
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | abeq | A. x (p <-> q) -> {x | p} == {x | q} |
|
| 2 | hyp h | G -> (p <-> q) |
|
| 3 | 2 | iald | G -> A. x (p <-> q) |
| 4 | 1, 3 | syl | G -> {x | p} == {x | q} |