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Theorem nfan1 2208
Description: A closed form of nfan 1901. (Contributed by Mario Carneiro, 3-Oct-2016.) df-nf 1786 changed. (Revised by Wolf Lammen, 18-Sep-2021.) (Proof shortened by Wolf Lammen, 7-Jul-2022.)
Hypotheses
Ref Expression
nfim1.1 𝑥𝜑
nfim1.2 (𝜑 → Ⅎ𝑥𝜓)
Assertion
Ref Expression
nfan1 𝑥(𝜑𝜓)

Proof of Theorem nfan1
StepHypRef Expression
1 df-an 396 . 2 ((𝜑𝜓) ↔ ¬ (𝜑 → ¬ 𝜓))
2 nfim1.1 . . . 4 𝑥𝜑
3 nfim1.2 . . . . 5 (𝜑 → Ⅎ𝑥𝜓)
43nfnd 1860 . . . 4 (𝜑 → Ⅎ𝑥 ¬ 𝜓)
52, 4nfim1 2207 . . 3 𝑥(𝜑 → ¬ 𝜓)
65nfn 1859 . 2 𝑥 ¬ (𝜑 → ¬ 𝜓)
71, 6nfxfr 1855 1 𝑥(𝜑𝜓)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 395  wnf 1785
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1912  ax-6 1969  ax-7 2010  ax-12 2185
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 849  df-ex 1782  df-nf 1786
This theorem is referenced by:  sb4b  2479  ralcom2  3339  sbcralt  3810  sbcrext  3811  csbiebt  3866  riota5f  7352  axrepndlem1  10515  axrepndlem2  10516  axunnd  10519  axpowndlem2  10521  axpowndlem3  10522  axpowndlem4  10523  axregndlem2  10526  axinfndlem1  10528  axinfnd  10529  axacndlem4  10533  axacndlem5  10534  axacnd  10535  fproddivf  15952  nfan1c  35215  axtcond  36660  mh-setindnd  36719  wl-sbcom2d-lem1  37884  wl-mo2df  37895  wl-eudf  37897  wl-mo3t  37901
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