Theorem impbi ≪ | index | src | ≫ 

theorem impbi (a b c: wff): $ a -> (b <-> c) $ > $ a /\ b -> c $;
StepHypRefExpression
1 hyp h 
a -> (b <-> c)
2 1 bi1d 
a -> b -> c
3 2 imp 
a /\ b -> c

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)