theorem bian2rexi (c: wff) {x: nat} (p a b: wff x): $ a <-> b /\ c $ > $ E. x (p /\ a) <-> E. x (p /\ b) /\ c $;
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | hyp h | a <-> b /\ c |
|
2 | 1 | a1i | p -> (a <-> b /\ c) |
3 | 2 | bian2rexa | E. x (p /\ a) <-> E. x (p /\ b) /\ c |