Theorem a2i ≪ | index | src | ≫ 

theorem a2i (a b c: wff): $ a -> b -> c $ > $ (a -> b) -> a -> c $;
StepHypRefExpression
1 ax_2 
(a -> b -> c) -> (a -> b) -> a -> c
2 hyp h 
a -> b -> c
3 1, 2 ax_mp 
(a -> b) -> a -> c

Axiom use

axs_prop_calc (ax_2, ax_mp)