Theorem notnot1 ≪ | index | src | ≫

theorem notnot1 (a: wff): $ a -> ~~a $;

Step	Hyp	Ref	Expression
1		con2	(~a -> ~a) -> a -> ~~a
2		id	~a -> ~a
3	1, 2	ax_mp	a -> ~~a

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)