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Metamath Proof Explorer

Theorem nfia1

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

		Ref	Expression
	Assertion	nfia1	$⊢ Ⅎ x (\forall x φ \to \forall x ψ)$

Step	Hyp	Ref	Expression
1		nfa1	$⊢ Ⅎ x \forall x φ$
2		nfa1	$⊢ Ⅎ x \forall x ψ$
3	1 2	nfim	$⊢ Ⅎ x (\forall x φ \to \forall x ψ)$