Theorem nfsbs ≪ | index | src | ≫

theorem nfsbs {x y: nat} (a: nat) (A: set x y):
  $ FS/ x A $ >
  $ FS/ x S[a / y] A $;

Step	Hyp	Ref	Expression
1		nfnv	FN/ x a
2		hyp h	FS/ x A
3	1, 2	nfsbsh	FS/ x S[a / y] A

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp, itru), axs_pred_calc (ax_gen, ax_4, ax_5, ax_6, ax_7, ax_10, ax_11, ax_12), axs_set (elab, ax_8)