Theorem bian11i | index | src |

theorem bian11i (a b c d: wff): $ a <-> b /\ c $ > $ a /\ d <-> b /\ (c /\ d) $;
StepHypRefExpression
1 bitr
(a /\ d <-> b /\ c /\ d) -> (b /\ c /\ d <-> b /\ (c /\ d)) -> (a /\ d <-> b /\ (c /\ d))
2 hyp h
a <-> b /\ c
3 2 aneq1i
a /\ d <-> b /\ c /\ d
4 1, 3 ax_mp
(b /\ c /\ d <-> b /\ (c /\ d)) -> (a /\ d <-> b /\ (c /\ d))
5 anass
b /\ c /\ d <-> b /\ (c /\ d)
6 4, 5 ax_mp
a /\ d <-> b /\ (c /\ d)

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)