theorem ifpeq1 (_p1 _p2 a b: wff):
$ (_p1 <-> _p2) -> (ifp _p1 a b <-> ifp _p2 a b) $;
| Step | Hyp | Ref | Expression |
|---|
| 1 |
|
id |
(_p1 <-> _p2) -> (_p1 <-> _p2) |
| 2 |
1 |
ifpeq1d |
(_p1 <-> _p2) -> (ifp _p1 a b <-> ifp _p2 a b) |
Axiom use
axs_prop_calc
(ax_1,
ax_2,
ax_3,
ax_mp)