Theorem nfsbn ≪ | index | src | ≫

theorem nfsbn {x y: nat} (a: nat) (b: nat x y):
  $ FN/ x b $ >
  $ FN/ x N[a / y] b $;

Step	Hyp	Ref	Expression
1		nfnv	FN/ x a
2		hyp h	FN/ x b
3	1, 2	nfsbnh	FN/ x N[a / y] b

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), axs_the (theid, the0)