Theorem nfndOLD 2247

Description: Obsolete proof of nfnd 1825 as of 6-Oct-2021. (Contributed by Mario Carneiro, 24-Sep-2016.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypothesis

Ref	Expression
nfndOLD.1	⊢ (𝜑 → Ⅎ𝑥𝜓)

Assertion

Ref	Expression
nfndOLD	⊢ (𝜑 → Ⅎ𝑥 ¬ 𝜓)

Proof of Theorem nfndOLD

Step	Hyp	Ref	Expression
1		nfndOLD.1	. 2 ⊢ (𝜑 → Ⅎ𝑥𝜓)
2		nfntOLD 2245	. 2 ⊢ (Ⅎ𝑥𝜓 → Ⅎ𝑥 ¬ 𝜓)
3	1, 2	syl 17	1 ⊢ (𝜑 → Ⅎ𝑥 ¬ 𝜓)

Syntax hints:  ¬ wn 3   → wi 4  ℲwnfOLD 1749

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1762  ax-4 1777  ax-5 1879  ax-6 1945  ax-7 1981  ax-10 2059  ax-12 2087

This theorem depends on definitions:  df-bi 197  df-or 384  df-ex 1745  df-nf 1750  df-nfOLD 1761

This theorem is referenced by:  nfandOLD  2268