theorem syl5bir (a b c d: wff): $ c <-> b $ > $ a -> c -> d $ > $ a -> b -> d $;
| Step | Hyp | Ref | Expression |
|---|
| 1 |
|
bicom |
(c <-> b) -> (b <-> c) |
| 2 |
|
hyp h1 |
c <-> b |
| 3 |
1, 2 |
ax_mp |
b <-> c |
| 4 |
|
hyp h2 |
a -> c -> d |
| 5 |
3, 4 |
syl5bi |
a -> b -> d |
Axiom use
axs_prop_calc
(ax_1,
ax_2,
ax_3,
ax_mp)