Theorem wl-nfalv

Description: If x is not present in ph , it is not free in A. y ph . (Contributed by Wolf Lammen, 11-Jan-2020)

	Ref	Expression
Assertion	wl-nfalv	$$⊢Ⅎx\forall y\phi$$

Proof

Step	Hyp	Ref	Expression
1		ax-5	$$⊢\phi \to \forall x\phi$$
2	1	hbal	$$⊢\forall y\phi \to \forall x\forall y\phi$$
3	2	nf5i	$$⊢Ⅎx\forall y\phi$$