Theorem bian21da ≪ | index | src | ≫

theorem bian21da (G a b c d: wff):
  $ G /\ d -> (a <-> b /\ c) $ >
  $ G -> (a /\ d <-> b /\ d /\ c) $;

Step	Hyp	Ref	Expression
1		anrass	b /\ c /\ d <-> b /\ d /\ c
2		hyp h	G /\ d -> (a <-> b /\ c)
3	2	aneq1da	G -> (a /\ d <-> b /\ c /\ d)
4	1, 3	syl6bb	G -> (a /\ d <-> b /\ d /\ c)

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)