theorem iexde {x: nat} (G: wff) (a: nat) (b: wff x):
$ G /\ x = a -> b $ >
$ G -> E. x b $;
| Step | Hyp | Ref | Expression |
|---|
| 1 |
|
nfv |
F/ x G |
| 2 |
|
hyp e |
G /\ x = a -> b |
| 3 |
1, 2 |
iexdeh |
G -> E. x b |
Axiom use
axs_prop_calc
(ax_1,
ax_2,
ax_3,
ax_mp),
axs_pred_calc
(ax_gen,
ax_4,
ax_5,
ax_6,
ax_7,
ax_12)