Theorem cbvsb ≪ | index | src | ≫

theorem cbvsb {x y: nat} (a: nat) (p: wff x) (q: wff y):
  $ x = y -> (p <-> q) $ >
  $ [a / x] p <-> [a / y] q $;

Step	Hyp	Ref	Expression
1		nfv	F/ y p
2		nfv	F/ x q
3		hyp e	x = y -> (p <-> q)
4	1, 2, 3	cbvsbh	[a / x] p <-> [a / y] q

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp), axs_pred_calc (ax_gen, ax_4, ax_5, ax_6, ax_7, ax_10, ax_11, ax_12)