Theorem nfia1

Description: Lemma 23 of Monk2 p. 114. (Contributed by Mario Carneiro, 24-Sep-2016)

	Ref	Expression
Assertion	nfia1	$$⊢Ⅎx\left(\forall x\phi \to \forall x\psi \right)$$

Proof

Step	Hyp	Ref	Expression
1		nfa1	$$⊢Ⅎx\forall x\phi$$
2		nfa1	$$⊢Ⅎx\forall x\psi$$
3	1 2	nfim	$$⊢Ⅎx\left(\forall x\phi \to \forall x\psi \right)$$