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Theorem nfiunya 3809
Description: Bound-variable hypothesis builder for indexed union. (Contributed by Mario Carneiro, 25-Jan-2014.)
Hypotheses
Ref Expression
nfiunya.1 𝑦𝐴
nfiunya.2 𝑦𝐵
Assertion
Ref Expression
nfiunya 𝑦 𝑥𝐴 𝐵
Distinct variable group:   𝑥,𝐴
Allowed substitution hints:   𝐴(𝑦)   𝐵(𝑥,𝑦)

Proof of Theorem nfiunya
Dummy variable 𝑧 is distinct from all other variables.
StepHypRef Expression
1 df-iun 3783 . 2 𝑥𝐴 𝐵 = {𝑧 ∣ ∃𝑥𝐴 𝑧𝐵}
2 nfiunya.1 . . . 4 𝑦𝐴
3 nfiunya.2 . . . . 5 𝑦𝐵
43nfcri 2250 . . . 4 𝑦 𝑧𝐵
52, 4nfrexya 2449 . . 3 𝑦𝑥𝐴 𝑧𝐵
65nfab 2261 . 2 𝑦{𝑧 ∣ ∃𝑥𝐴 𝑧𝐵}
71, 6nfcxfr 2253 1 𝑦 𝑥𝐴 𝐵
Colors of variables: wff set class
Syntax hints:  wcel 1463  {cab 2101  wnfc 2243  wrex 2392   ciun 3781
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-io 681  ax-5 1406  ax-7 1407  ax-gen 1408  ax-ie1 1452  ax-ie2 1453  ax-8 1465  ax-10 1466  ax-11 1467  ax-i12 1468  ax-bndl 1469  ax-4 1470  ax-17 1489  ax-i9 1493  ax-ial 1497  ax-i5r 1498  ax-ext 2097
This theorem depends on definitions:  df-bi 116  df-tru 1317  df-nf 1420  df-sb 1719  df-clab 2102  df-cleq 2108  df-clel 2111  df-nfc 2245  df-rex 2397  df-iun 3783
This theorem is referenced by: (None)
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