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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  3348  sbcralt  3823  sbcrext  3824  csbiebt  3879  riota5f  7345  axrepndlem1  10507  axrepndlem2  10508  axunnd  10511  axpowndlem2  10513  axpowndlem3  10514  axpowndlem4  10515  axregndlem2  10518  axinfndlem1  10520  axinfnd  10521  axacndlem4  10525  axacndlem5  10526  axacnd  10527  fproddivf  15914  nfan1c  35231  mh-setindnd  36669  wl-sbcom2d-lem1  37766  wl-mo2df  37777  wl-eudf  37779  wl-mo3t  37783
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