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Theorem nfif 3419
Description: Bound-variable hypothesis builder for a conditional operator. (Contributed by NM, 16-Feb-2005.) (Proof shortened by Andrew Salmon, 26-Jun-2011.)
Hypotheses
Ref Expression
nfif.1 𝑥𝜑
nfif.2 𝑥𝐴
nfif.3 𝑥𝐵
Assertion
Ref Expression
nfif 𝑥if(𝜑, 𝐴, 𝐵)

Proof of Theorem nfif
StepHypRef Expression
1 nfif.1 . . . 4 𝑥𝜑
21a1i 9 . . 3 (⊤ → Ⅎ𝑥𝜑)
3 nfif.2 . . . 4 𝑥𝐴
43a1i 9 . . 3 (⊤ → 𝑥𝐴)
5 nfif.3 . . . 4 𝑥𝐵
65a1i 9 . . 3 (⊤ → 𝑥𝐵)
72, 4, 6nfifd 3418 . 2 (⊤ → 𝑥if(𝜑, 𝐴, 𝐵))
87mptru 1298 1 𝑥if(𝜑, 𝐴, 𝐵)
Colors of variables: wff set class
Syntax hints:  wtru 1290  wnf 1394  wnfc 2215  ifcif 3393
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-in1 579  ax-in2 580  ax-io 665  ax-5 1381  ax-7 1382  ax-gen 1383  ax-ie1 1427  ax-ie2 1428  ax-8 1440  ax-10 1441  ax-11 1442  ax-i12 1443  ax-bndl 1444  ax-4 1445  ax-17 1464  ax-i9 1468  ax-ial 1472  ax-i5r 1473  ax-ext 2070
This theorem depends on definitions:  df-bi 115  df-tru 1292  df-fal 1295  df-nf 1395  df-sb 1693  df-clab 2075  df-cleq 2081  df-clel 2084  df-nfc 2217  df-if 3394
This theorem is referenced by:  nfsum1  10745  nfsum  10746  isumrblem  10765  isummolem2a  10771  zisum  10774  fisum  10778  isumss  10783  isumss2  10785  fisumcvg2  10786  fsum3cvg2  10787
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