Theorem biidd ≪ | index | src | ≫

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

Step	Hyp	Ref	Expression
1		biid	b <-> b
2	1	a1i	a -> (b <-> b)

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)