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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
StepHypRef Expression
1 nfndOLD.1 . 2 (𝜑 → Ⅎ𝑥𝜓)
2 nfntOLD 2245 . 2 (Ⅎ𝑥𝜓 → Ⅎ𝑥 ¬ 𝜓)
31, 2syl 17 1 (𝜑 → Ⅎ𝑥 ¬ 𝜓)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wnfOLD 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
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