theorem bian1rexa (b: wff) {x: nat} (p a c: wff x):
$ p -> (a <-> b /\ c) $ >
$ E. x (p /\ a) <-> b /\ E. x (p /\ c) $;
Step | Hyp | Ref | Expression |
1 |
|
bitr |
(E. x (p /\ a) <-> E. x (p /\ (b /\ c))) -> (E. x (p /\ (b /\ c)) <-> b /\ E. x (p /\ c)) -> (E. x (p /\ a) <-> b /\ E. x (p /\ c)) |
2 |
|
hyp h |
p -> (a <-> b /\ c) |
3 |
2 |
rexeqa |
E. x (p /\ a) <-> E. x (p /\ (b /\ c)) |
4 |
1, 3 |
ax_mp |
(E. x (p /\ (b /\ c)) <-> b /\ E. x (p /\ c)) -> (E. x (p /\ a) <-> b /\ E. x (p /\ c)) |
5 |
|
rexan1 |
E. x (p /\ (b /\ c)) <-> b /\ E. x (p /\ c) |
6 |
4, 5 |
ax_mp |
E. x (p /\ a) <-> b /\ E. x (p /\ c) |
Axiom use
axs_prop_calc
(ax_1,
ax_2,
ax_3,
ax_mp),
axs_pred_calc
(ax_gen,
ax_4,
ax_5)