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Theorem nfre1 2513
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 2454 . 2 (∃𝑥𝐴 𝜑 ↔ ∃𝑥(𝑥𝐴𝜑))
2 nfe1 1489 . 2 𝑥𝑥(𝑥𝐴𝜑)
31, 2nfxfr 1467 1 𝑥𝑥𝐴 𝜑
Colors of variables: wff set class
Syntax hints:  wa 103  wnf 1453  wex 1485  wcel 2141  wrex 2449
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1440  ax-gen 1442  ax-ie1 1486
This theorem depends on definitions:  df-bi 116  df-nf 1454  df-rex 2454
This theorem is referenced by:  r19.29an  2612  nfiu1  3903  fun11iun  5463  eusvobj2  5839  fodjuomnilemdc  7120  ismkvnex  7131  prarloclem3step  7458  prmuloc2  7529  ltexprlemm  7562  caucvgprprlemaddq  7670  caucvgsrlemgt1  7757  axpre-suploclemres  7863  supinfneg  9554  infsupneg  9555  lbzbi  9575  divalglemeunn  11880  divalglemeuneg  11882  bezoutlemmain  11953  bezout  11966  pw1nct  14036  isomninnlem  14062  trirec0  14076  ismkvnnlem  14084
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