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Metamath Proof Explorer

Theorem nfnd

Description: Deduction associated with nfnt . (Contributed by Mario Carneiro, 24-Sep-2016)

		Ref	Expression
	Hypothesis	nfnd.1	$⊢ φ \to Ⅎ x ψ$
	Assertion	nfnd	$⊢ φ \to Ⅎ x \neg ψ$

Step	Hyp	Ref	Expression
1		nfnd.1	$⊢ φ \to Ⅎ x ψ$
2		nfnt	$⊢ Ⅎ x ψ \to Ⅎ x \neg ψ$
3	1 2	syl	$⊢ φ \to Ⅎ x \neg ψ$