Theorem mtbid | index | src |

theorem mtbid (a b c: wff): $ a -> (b <-> c) $ > $ a -> ~b $ > $ a -> ~c $;
StepHypRefExpression
1 hyp h2
a -> ~b
2 hyp h1
a -> (b <-> c)
3 2 bi2d
a -> c -> b
4 1, 3 mtd
a -> ~c

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)