theorem oridm (a: wff): $ a \/ a <-> a $;
| Step | Hyp | Ref | Expression |
|---|
| 1 |
|
eor |
(a -> a) -> (a -> a) -> a \/ a -> a |
| 2 |
|
id |
a -> a |
| 3 |
1, 2 |
ax_mp |
(a -> a) -> a \/ a -> a |
| 4 |
3, 2 |
ax_mp |
a \/ a -> a |
| 5 |
|
orl |
a -> a \/ a |
| 6 |
4, 5 |
ibii |
a \/ a <-> a |
Axiom use
axs_prop_calc
(ax_1,
ax_2,
ax_3,
ax_mp)