Theorem notan2 | index | src |

theorem notan2 (a b: wff): $ ~(a /\ b) <-> a -> ~b $;
StepHypRefExpression
1 bicom
(a -> ~b <-> ~(a /\ b)) -> (~(a /\ b) <-> a -> ~b)
2 notnot
a -> ~b <-> ~~(a -> ~b)
3 2 conv an
a -> ~b <-> ~(a /\ b)
4 1, 3 ax_mp
~(a /\ b) <-> a -> ~b

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)