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Theorem nfixp1 8469
 Description: The index variable in an indexed Cartesian product is not free. (Contributed by Jeff Madsen, 19-Jun-2011.) (Revised by Mario Carneiro, 15-Oct-2016.)
Assertion
Ref Expression
nfixp1 𝑥X𝑥𝐴 𝐵

Proof of Theorem nfixp1
Dummy variable 𝑦 is distinct from all other variables.
StepHypRef Expression
1 df-ixp 8449 . 2 X𝑥𝐴 𝐵 = {𝑦 ∣ (𝑦 Fn {𝑥𝑥𝐴} ∧ ∀𝑥𝐴 (𝑦𝑥) ∈ 𝐵)}
2 nfcv 2958 . . . . 5 𝑥𝑦
3 nfab1 2960 . . . . 5 𝑥{𝑥𝑥𝐴}
42, 3nffn 6426 . . . 4 𝑥 𝑦 Fn {𝑥𝑥𝐴}
5 nfra1 3186 . . . 4 𝑥𝑥𝐴 (𝑦𝑥) ∈ 𝐵
64, 5nfan 1900 . . 3 𝑥(𝑦 Fn {𝑥𝑥𝐴} ∧ ∀𝑥𝐴 (𝑦𝑥) ∈ 𝐵)
76nfab 2964 . 2 𝑥{𝑦 ∣ (𝑦 Fn {𝑥𝑥𝐴} ∧ ∀𝑥𝐴 (𝑦𝑥) ∈ 𝐵)}
81, 7nfcxfr 2956 1 𝑥X𝑥𝐴 𝐵
 Colors of variables: wff setvar class Syntax hints:   ∧ wa 399   ∈ wcel 2112  {cab 2779  Ⅎwnfc 2939  ∀wral 3109   Fn wfn 6323  ‘cfv 6328  Xcixp 8448 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1911  ax-6 1970  ax-7 2015  ax-8 2114  ax-9 2122  ax-10 2143  ax-11 2159  ax-12 2176  ax-ext 2773 This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-3an 1086  df-tru 1541  df-ex 1782  df-nf 1786  df-sb 2070  df-clab 2780  df-cleq 2794  df-clel 2873  df-nfc 2941  df-ral 3114  df-v 3446  df-dif 3887  df-un 3889  df-in 3891  df-ss 3901  df-nul 4247  df-if 4429  df-sn 4529  df-pr 4531  df-op 4535  df-br 5034  df-opab 5096  df-rel 5530  df-cnv 5531  df-co 5532  df-dm 5533  df-fun 6330  df-fn 6331  df-ixp 8449 This theorem is referenced by:  ixpiunwdom  9042  ptbasfi  22190  hoidmvlelem3  43233  hspdifhsp  43252  hoiqssbllem2  43259  hspmbllem2  43263  opnvonmbllem2  43269  iinhoiicc  43310  iunhoiioo  43312  vonioo  43318  vonicc  43321
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