Theorem an3l ≪ | index | src | ≫ 

theorem an3l (a b c d: wff): $ a /\ b /\ c /\ d -> a $;
StepHypRefExpression
1 anl 
a /\ b -> a
2 1 anwll 
a /\ b /\ c /\ d -> a

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)