Theorem bibin2 | index | src |

theorem bibin2 (a b: wff): $ ~b -> (a <-> b <-> ~a) $;
StepHypRefExpression
1 bicomb
a <-> b <-> (b <-> a)
2 bibin1
~b -> (b <-> a <-> ~a)
3 1, 2 syl5bb
~b -> (a <-> b <-> ~a)

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)