Theorem rsyl ≪ | index | src | ≫ 

theorem rsyl (a b c: wff): $ a -> b $ > $ b -> c $ > $ a -> c $;
StepHypRefExpression
1 hyp h2 
b -> c
2 hyp h1 
a -> b
3 1, 2 syl 
a -> c

Axiom use

axs_prop_calc (ax_1, ax_2, ax_mp)