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Theorem nf2 1555
Description: An alternative definition of df-nf 1347, which does not involve nested quantifiers on the same variable. (Contributed by Mario Carneiro, 24-Sep-2016.)
Assertion
Ref Expression
nf2  F/

Proof of Theorem nf2
StepHypRef Expression
1 df-nf 1347 . 2  F/
2 nfa1 1431 . . . 4  F/
32nfri 1409 . . 3
4319.23h 1384 . 2
51, 4bitri 173 1  F/
Colors of variables: wff set class
Syntax hints:   wi 4   wb 98  wal 1240   F/wnf 1346  wex 1378
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-gen 1335  ax-ie2 1380  ax-4 1397  ax-ial 1424
This theorem depends on definitions:  df-bi 110  df-nf 1347
This theorem is referenced by:  nf3  1556  nf4dc  1557  nf4r  1558  eusv2i  4153
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