Theorem nfi ≪ | index | src | ≫ 

theorem nfi {x: nat} (a: wff x): $ F/ x a $ > $ a -> A. x a $;
StepHypRefExpression
1 eal 
A. x (a -> A. x a) -> a -> A. x a
2 hyp h 
F/ x a
3 2 conv nf 
A. x (a -> A. x a)
4 1, 3 ax_mp 
a -> A. x a

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp), axs_pred_calc (ax_gen, ax_4, ax_5, ax_6, ax_7, ax_12)