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Theorem nfre1 2548
Description: 𝑥 is not free in 𝑥𝐴𝜑. (Contributed by NM, 19-Mar-1997.) (Revised by Mario Carneiro, 7-Oct-2016.)
Assertion
Ref Expression
nfre1 𝑥𝑥𝐴 𝜑

Proof of Theorem nfre1
StepHypRef Expression
1 df-rex 2489 . 2 (∃𝑥𝐴 𝜑 ↔ ∃𝑥(𝑥𝐴𝜑))
2 nfe1 1518 . 2 𝑥𝑥(𝑥𝐴𝜑)
31, 2nfxfr 1496 1 𝑥𝑥𝐴 𝜑
Colors of variables: wff set class
Syntax hints:  wa 104  wnf 1482  wex 1514  wcel 2175  wrex 2484
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1469  ax-gen 1471  ax-ie1 1515
This theorem depends on definitions:  df-bi 117  df-nf 1483  df-rex 2489
This theorem is referenced by:  r19.29an  2647  nfiu1  3956  fun11iun  5542  eusvobj2  5929  fodjuomnilemdc  7245  ismkvnex  7256  prarloclem3step  7608  prmuloc2  7679  ltexprlemm  7712  caucvgprprlemaddq  7820  caucvgsrlemgt1  7907  axpre-suploclemres  8013  supinfneg  9715  infsupneg  9716  lbzbi  9736  divalglemeunn  12174  divalglemeuneg  12176  bezoutlemmain  12261  bezout  12274  lss1d  14087  pw1nct  15873  isomninnlem  15902  trirec0  15916  ismkvnnlem  15924
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