Theorem bitr3gi | index | src |

theorem bitr3gi (a b c d: wff):
  $ a <-> c $ >
  $ b <-> d $ >
  $ a <-> b $ >
  $ c <-> d $;
StepHypRefExpression
1 bitr3
(a <-> c) -> (a <-> d) -> (c <-> d)
2 hyp h1
a <-> c
3 1, 2 ax_mp
(a <-> d) -> (c <-> d)
4 bitr
(a <-> b) -> (b <-> d) -> (a <-> d)
5 hyp h
a <-> b
6 4, 5 ax_mp
(b <-> d) -> (a <-> d)
7 hyp h2
b <-> d
8 6, 7 ax_mp
a <-> d
9 3, 8 ax_mp
c <-> d

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)