Theorem imim ≪ | index | src | ≫ 

theorem imim (a b c d: wff): $ (a -> b) -> (c -> d) -> (b -> c) -> a -> d $;
StepHypRefExpression
1 imim2 
(c -> d) -> (b -> c) -> b -> d
2 imim1 
(a -> b) -> (b -> d) -> a -> d
3 2 imim2d 
(a -> b) -> ((b -> c) -> b -> d) -> (b -> c) -> a -> d
4 1, 3 syl5 
(a -> b) -> (c -> d) -> (b -> c) -> a -> d

Axiom use

axs_prop_calc (ax_1, ax_2, ax_mp)