Theorem bi2 ≪ | index | src | ≫

theorem bi2 (a b: wff): $ (a <-> b) -> b -> a $;

Step	Hyp	Ref	Expression
1		anr	(a -> b) /\ (b -> a) -> b -> a
2	1	conv iff	(a <-> b) -> b -> a

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)