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Theorem nfan1 2238
Description: A closed form of nfan 1932. (Contributed by Mario Carneiro, 3-Oct-2016.) df-nf 1817 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 402 . 2 ((𝜑𝜓) ↔ ¬ (𝜑 → ¬ 𝜓))
2 nfim1.1 . . . 4 𝑥𝜑
3 nfim1.2 . . . . 5 (𝜑 → Ⅎ𝑥𝜓)
43nfnd 1891 . . . 4 (𝜑 → Ⅎ𝑥 ¬ 𝜓)
52, 4nfim1 2237 . . 3 𝑥(𝜑 → ¬ 𝜓)
65nfn 1890 . 2 𝑥 ¬ (𝜑 → ¬ 𝜓)
71, 6nfxfr 1886 1 𝑥(𝜑𝜓)
Colors of variables:    wff setvar class
This proof depends on syntax axioms:  ¬ wn 3  wi 4  wa 401  wnf 1816
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842  ax-5 1943  ax-6 2000  ax-7 2041  ax-12 2215
This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-ex 1813  df-nf 1817
This theorem is used by:  sb4b  2506  ralcom2  3364  sbcralt  3822  sbcrext  3823  csbiebt  3879  riota5f  7401  axrepndlem1  10604  axrepndlem2  10605  axunnd  10608  axpowndlem2  10610  axpowndlem3  10611  axpowndlem4  10612  axregndlem2  10615  axinfndlem1  10617  axinfnd  10618  axacndlem4  10622  axacndlem5  10623  axacnd  10624  fproddivf  16078  nfan1c  35569  axtcond  37084  mh-setindnd  37143  wl-sbcom2d-lem1  38309  wl-mo2df  38320  wl-eudf  38322  wl-mo3t  38326
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