Theorem nfnth 1805

Description: No variable is (effectively) free in a non-theorem. (Contributed by Mario Carneiro, 6-Dec-2016.) df-nf 1787 changed. (Revised by Wolf Lammen, 12-Sep-2021.)

Hypothesis

Ref	Expression
nfnth.1	⊢ ¬ 𝜑

Assertion

Ref	Expression
nfnth	⊢ Ⅎ𝑥𝜑

Proof of Theorem nfnth

Step	Hyp	Ref	Expression
1		nfntht2 1797	. 2 ⊢ (∀𝑥 ¬ 𝜑 → Ⅎ𝑥𝜑)
2		nfnth.1	. 2 ⊢ ¬ 𝜑
3	1, 2	mpg 1800	1 ⊢ Ⅎ𝑥𝜑

Syntax hints:  ¬ wn 3  Ⅎwnf 1786

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1798

This theorem depends on definitions:  df-bi 206  df-ex 1783  df-nf 1787

This theorem is referenced by:  nffal  1808  nd1  10343  nd2  10344