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Theorem nfiundg 48685
Description: Bound-variable hypothesis builder for indexed union. Usage of this theorem is discouraged because it depends on ax-13 2374, see nfiund 48684 for a weaker version that does not require it. (Contributed by Emmett Weisz, 6-Dec-2019.) (New usage is discouraged.)
Hypotheses
Ref Expression
nfiundg.1 𝑥𝜑
nfiundg.2 (𝜑𝑦𝐴)
nfiundg.3 (𝜑𝑦𝐵)
Assertion
Ref Expression
nfiundg (𝜑𝑦 𝑥𝐴 𝐵)

Proof of Theorem nfiundg
Dummy variable 𝑧 is distinct from all other variables.
StepHypRef Expression
1 df-iun 5021 . 2 𝑥𝐴 𝐵 = {𝑧 ∣ ∃𝑥𝐴 𝑧𝐵}
2 nfv 1913 . . 3 𝑧𝜑
3 nfiundg.1 . . . 4 𝑥𝜑
4 nfiundg.2 . . . 4 (𝜑𝑦𝐴)
5 nfiundg.3 . . . . 5 (𝜑𝑦𝐵)
65nfcrd 2897 . . . 4 (𝜑 → Ⅎ𝑦 𝑧𝐵)
73, 4, 6nfrexd 3376 . . 3 (𝜑 → Ⅎ𝑦𝑥𝐴 𝑧𝐵)
82, 7nfabd 2930 . 2 (𝜑𝑦{𝑧 ∣ ∃𝑥𝐴 𝑧𝐵})
91, 8nfcxfrd 2903 1 (𝜑𝑦 𝑥𝐴 𝐵)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wnf 1781  wcel 2103  {cab 2711  wnfc 2888  wrex 3072   ciun 5019
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1793  ax-4 1807  ax-5 1909  ax-6 1967  ax-7 2007  ax-8 2105  ax-9 2113  ax-10 2136  ax-11 2153  ax-12 2173  ax-13 2374  ax-ext 2705
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 847  df-tru 1540  df-ex 1778  df-nf 1782  df-sb 2065  df-clab 2712  df-cleq 2726  df-clel 2813  df-nfc 2890  df-ral 3064  df-rex 3073  df-iun 5021
This theorem is referenced by: (None)
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