Theorem binth ≪ | index | src | ≫

theorem binth (a b: wff): $ ~a -> ~b -> (a <-> b) $;

Step	Hyp	Ref	Expression
1		anl	~a /\ ~b -> ~a
2		anr	~a /\ ~b -> ~b
3	1, 2	binthd	~a /\ ~b -> (a <-> b)
4	3	exp	~a -> ~b -> (a <-> b)

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)