theorem rexeqi {x: nat} (p a b: wff x):
$ a <-> b $ >
$ E. x (p /\ a) <-> E. x (p /\ b) $;
| Step | Hyp | Ref | Expression |
|---|
| 1 |
|
hyp h |
a <-> b |
| 2 |
1 |
aneq2i |
p /\ a <-> p /\ b |
| 3 |
2 |
exeqi |
E. x (p /\ a) <-> E. x (p /\ b) |
Axiom use
axs_prop_calc
(ax_1,
ax_2,
ax_3,
ax_mp),
axs_pred_calc
(ax_gen,
ax_4)