Theorem con2b | index | src |

theorem con2b (a b: wff): $ (a <-> ~b) -> (b <-> ~a) $;
StepHypRefExpression
1 bi1
(a <-> ~b) -> a -> ~b
2 1 con2d
(a <-> ~b) -> b -> ~a
3 bi2
(a <-> ~b) -> ~b -> a
4 3 con1d
(a <-> ~b) -> ~a -> b
5 2, 4 ibid
(a <-> ~b) -> (b <-> ~a)

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)