theorem syl5ibrcom (a b c d: wff):
$ c -> (b <-> d) $ >
$ a -> d $ >
$ a -> c -> b $;
| Step | Hyp | Ref | Expression |
|---|
| 1 |
|
hyp h2 |
a -> d |
| 2 |
|
hyp h1 |
c -> (b <-> d) |
| 3 |
2 |
bi2d |
c -> d -> b |
| 4 |
1, 3 |
syl5 |
c -> a -> b |
| 5 |
4 |
com12 |
a -> c -> b |
Axiom use
axs_prop_calc
(ax_1,
ax_2,
ax_3,
ax_mp)