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Theorem nfre1 2573
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 2514 . 2 (∃𝑥𝐴 𝜑 ↔ ∃𝑥(𝑥𝐴𝜑))
2 nfe1 1542 . 2 𝑥𝑥(𝑥𝐴𝜑)
31, 2nfxfr 1520 1 𝑥𝑥𝐴 𝜑
Colors of variables: wff set class
Syntax hints:  wa 104  wnf 1506  wex 1538  wcel 2200  wrex 2509
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 1493  ax-gen 1495  ax-ie1 1539
This theorem depends on definitions:  df-bi 117  df-nf 1507  df-rex 2514
This theorem is referenced by:  r19.29an  2673  nfiu1  3995  fun11iun  5595  eusvobj2  5993  fodjuomnilemdc  7322  ismkvnex  7333  prarloclem3step  7694  prmuloc2  7765  ltexprlemm  7798  caucvgprprlemaddq  7906  caucvgsrlemgt1  7993  axpre-suploclemres  8099  supinfneg  9802  infsupneg  9803  lbzbi  9823  divalglemeunn  12447  divalglemeuneg  12449  bezoutlemmain  12534  bezout  12547  lss1d  14362  pw1nct  16428  isomninnlem  16458  trirec0  16472  ismkvnnlem  16480
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