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Theorem nfan1 2196
Description: A closed form of nfan 1903. (Contributed by Mario Carneiro, 3-Oct-2016.) df-nf 1788 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 1862 . . . 4 (𝜑 → Ⅎ𝑥 ¬ 𝜓)
52, 4nfim1 2195 . . 3 𝑥(𝜑 → ¬ 𝜓)
65nfn 1861 . 2 𝑥 ¬ (𝜑 → ¬ 𝜓)
71, 6nfxfr 1856 1 𝑥(𝜑𝜓)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 395  wnf 1787
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1799  ax-4 1813  ax-5 1914  ax-6 1972  ax-7 2012  ax-12 2173
This theorem depends on definitions:  df-bi 206  df-an 396  df-or 844  df-ex 1784  df-nf 1788
This theorem is referenced by:  sb4b  2475  sb4bOLD  2476  ralcom2  3288  sbcralt  3801  sbcrext  3802  csbiebt  3858  riota5f  7241  axrepndlem1  10279  axrepndlem2  10280  axunnd  10283  axpowndlem2  10285  axpowndlem3  10286  axpowndlem4  10287  axregndlem2  10290  axinfndlem1  10292  axinfnd  10293  axacndlem4  10297  axacndlem5  10298  axacnd  10299  fproddivf  15625  wl-sbcom2d-lem1  35641  wl-mo2df  35652  wl-eudf  35654  wl-mo3t  35658  wl-ax11-lem4  35666  wl-ax11-lem6  35668
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