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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  2480  ralcom2  3340  sbcralt  3811  sbcrext  3812  csbiebt  3867  riota5f  7347  axrepndlem1  10510  axrepndlem2  10511  axunnd  10514  axpowndlem2  10516  axpowndlem3  10517  axpowndlem4  10518  axregndlem2  10521  axinfndlem1  10523  axinfnd  10524  axacndlem4  10528  axacndlem5  10529  axacnd  10530  fproddivf  15947  nfan1c  35235  axtcond  36680  mh-setindnd  36739  wl-sbcom2d-lem1  37904  wl-mo2df  37915  wl-eudf  37917  wl-mo3t  37921
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