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Theorem nfan1 2203
Description: A closed form of nfan 1900. (Contributed by Mario Carneiro, 3-Oct-2016.) df-nf 1785 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 1859 . . . 4 (𝜑 → Ⅎ𝑥 ¬ 𝜓)
52, 4nfim1 2202 . . 3 𝑥(𝜑 → ¬ 𝜓)
65nfn 1858 . 2 𝑥 ¬ (𝜑 → ¬ 𝜓)
71, 6nfxfr 1854 1 𝑥(𝜑𝜓)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 395  wnf 1784
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1968  ax-7 2009  ax-12 2180
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-ex 1781  df-nf 1785
This theorem is referenced by:  sb4b  2475  ralcom2  3343  sbcralt  3818  sbcrext  3819  csbiebt  3874  riota5f  7331  axrepndlem1  10483  axrepndlem2  10484  axunnd  10487  axpowndlem2  10489  axpowndlem3  10490  axpowndlem4  10491  axregndlem2  10494  axinfndlem1  10496  axinfnd  10497  axacndlem4  10501  axacndlem5  10502  axacnd  10503  fproddivf  15894  nfan1c  35085  wl-sbcom2d-lem1  37603  wl-mo2df  37614  wl-eudf  37616  wl-mo3t  37620
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