theorem casesd (a b c: wff): $ a -> b -> c $ > $ a -> ~b -> c $ > $ a -> c $;
| Step | Hyp | Ref | Expression |
|---|
| 1 |
|
hyp h1 |
a -> b -> c |
| 2 |
1 |
com12 |
b -> a -> c |
| 3 |
|
hyp h2 |
a -> ~b -> c |
| 4 |
3 |
com12 |
~b -> a -> c |
| 5 |
2, 4 |
cases |
a -> c |
Axiom use
axs_prop_calc
(ax_1,
ax_2,
ax_3,
ax_mp)