Theorem aneq1d ≪ | index | src | ≫ 

theorem aneq1d (a b c d: wff):
  $ a -> (b <-> c) $ >
  $ a -> (b /\ d <-> c /\ d) $;
StepHypRefExpression
1 hyp h 
a -> (b <-> c)
2 biidd 
a -> (d <-> d)
3 1, 2 aneqd 
a -> (b /\ d <-> c /\ d)

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)