theorem oreq2d (_G a _b1 _b2: wff):
$ _G -> (_b1 <-> _b2) $ >
$ _G -> (a \/ _b1 <-> a \/ _b2) $;
| Step | Hyp | Ref | Expression |
|---|
| 1 |
|
biidd |
_G -> (a <-> a) |
| 2 |
|
hyp _h |
_G -> (_b1 <-> _b2) |
| 3 |
1, 2 |
oreqd |
_G -> (a \/ _b1 <-> a \/ _b2) |
Axiom use
axs_prop_calc
(ax_1,
ax_2,
ax_3,
ax_mp)