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Theorem iunfi 9242
Description: The finite union of finite sets is finite. Exercise 13 of [Enderton] p. 144. This is the indexed union version of unifi 9243. Note that 𝐵 depends on 𝑥, i.e. can be thought of as 𝐵(𝑥). (Contributed by NM, 23-Mar-2006.) (Proof shortened by Mario Carneiro, 31-Aug-2015.)
Assertion
Ref Expression
iunfi ((𝐴 ∈ Fin ∧ ∀𝑥𝐴 𝐵 ∈ Fin) → 𝑥𝐴 𝐵 ∈ Fin)
Distinct variable group:   𝑥,𝐴
Allowed substitution hint:   𝐵(𝑥)

Proof of Theorem iunfi
Dummy variables 𝑤 𝑦 𝑧 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 raleq 3307 . . . 4 (𝑤 = ∅ → (∀𝑥𝑤 𝐵 ∈ Fin ↔ ∀𝑥 ∈ ∅ 𝐵 ∈ Fin))
2 iuneq1 4968 . . . . . 6 (𝑤 = ∅ → 𝑥𝑤 𝐵 = 𝑥 ∈ ∅ 𝐵)
3 0iun 5021 . . . . . 6 𝑥 ∈ ∅ 𝐵 = ∅
42, 3eqtrdi 2793 . . . . 5 (𝑤 = ∅ → 𝑥𝑤 𝐵 = ∅)
54eleq1d 2822 . . . 4 (𝑤 = ∅ → ( 𝑥𝑤 𝐵 ∈ Fin ↔ ∅ ∈ Fin))
61, 5imbi12d 344 . . 3 (𝑤 = ∅ → ((∀𝑥𝑤 𝐵 ∈ Fin → 𝑥𝑤 𝐵 ∈ Fin) ↔ (∀𝑥 ∈ ∅ 𝐵 ∈ Fin → ∅ ∈ Fin)))
7 raleq 3307 . . . 4 (𝑤 = 𝑦 → (∀𝑥𝑤 𝐵 ∈ Fin ↔ ∀𝑥𝑦 𝐵 ∈ Fin))
8 iuneq1 4968 . . . . 5 (𝑤 = 𝑦 𝑥𝑤 𝐵 = 𝑥𝑦 𝐵)
98eleq1d 2822 . . . 4 (𝑤 = 𝑦 → ( 𝑥𝑤 𝐵 ∈ Fin ↔ 𝑥𝑦 𝐵 ∈ Fin))
107, 9imbi12d 344 . . 3 (𝑤 = 𝑦 → ((∀𝑥𝑤 𝐵 ∈ Fin → 𝑥𝑤 𝐵 ∈ Fin) ↔ (∀𝑥𝑦 𝐵 ∈ Fin → 𝑥𝑦 𝐵 ∈ Fin)))
11 raleq 3307 . . . 4 (𝑤 = (𝑦 ∪ {𝑧}) → (∀𝑥𝑤 𝐵 ∈ Fin ↔ ∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin))
12 iuneq1 4968 . . . . 5 (𝑤 = (𝑦 ∪ {𝑧}) → 𝑥𝑤 𝐵 = 𝑥 ∈ (𝑦 ∪ {𝑧})𝐵)
1312eleq1d 2822 . . . 4 (𝑤 = (𝑦 ∪ {𝑧}) → ( 𝑥𝑤 𝐵 ∈ Fin ↔ 𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin))
1411, 13imbi12d 344 . . 3 (𝑤 = (𝑦 ∪ {𝑧}) → ((∀𝑥𝑤 𝐵 ∈ Fin → 𝑥𝑤 𝐵 ∈ Fin) ↔ (∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin → 𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin)))
15 raleq 3307 . . . 4 (𝑤 = 𝐴 → (∀𝑥𝑤 𝐵 ∈ Fin ↔ ∀𝑥𝐴 𝐵 ∈ Fin))
16 iuneq1 4968 . . . . 5 (𝑤 = 𝐴 𝑥𝑤 𝐵 = 𝑥𝐴 𝐵)
1716eleq1d 2822 . . . 4 (𝑤 = 𝐴 → ( 𝑥𝑤 𝐵 ∈ Fin ↔ 𝑥𝐴 𝐵 ∈ Fin))
1815, 17imbi12d 344 . . 3 (𝑤 = 𝐴 → ((∀𝑥𝑤 𝐵 ∈ Fin → 𝑥𝑤 𝐵 ∈ Fin) ↔ (∀𝑥𝐴 𝐵 ∈ Fin → 𝑥𝐴 𝐵 ∈ Fin)))
19 0fin 9073 . . . 4 ∅ ∈ Fin
2019a1i 11 . . 3 (∀𝑥 ∈ ∅ 𝐵 ∈ Fin → ∅ ∈ Fin)
21 ssun1 4130 . . . . . . 7 𝑦 ⊆ (𝑦 ∪ {𝑧})
22 ssralv 4008 . . . . . . 7 (𝑦 ⊆ (𝑦 ∪ {𝑧}) → (∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin → ∀𝑥𝑦 𝐵 ∈ Fin))
2321, 22ax-mp 5 . . . . . 6 (∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin → ∀𝑥𝑦 𝐵 ∈ Fin)
2423imim1i 63 . . . . 5 ((∀𝑥𝑦 𝐵 ∈ Fin → 𝑥𝑦 𝐵 ∈ Fin) → (∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin → 𝑥𝑦 𝐵 ∈ Fin))
25 iunxun 5052 . . . . . . 7 𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 = ( 𝑥𝑦 𝐵 𝑥 ∈ {𝑧}𝐵)
26 nfcv 2905 . . . . . . . . . . 11 𝑦𝐵
27 nfcsb1v 3878 . . . . . . . . . . 11 𝑥𝑦 / 𝑥𝐵
28 csbeq1a 3867 . . . . . . . . . . 11 (𝑥 = 𝑦𝐵 = 𝑦 / 𝑥𝐵)
2926, 27, 28cbviun 4994 . . . . . . . . . 10 𝑥 ∈ {𝑧}𝐵 = 𝑦 ∈ {𝑧}𝑦 / 𝑥𝐵
30 vex 3447 . . . . . . . . . . 11 𝑧 ∈ V
31 csbeq1 3856 . . . . . . . . . . 11 (𝑦 = 𝑧𝑦 / 𝑥𝐵 = 𝑧 / 𝑥𝐵)
3230, 31iunxsn 5049 . . . . . . . . . 10 𝑦 ∈ {𝑧}𝑦 / 𝑥𝐵 = 𝑧 / 𝑥𝐵
3329, 32eqtri 2765 . . . . . . . . 9 𝑥 ∈ {𝑧}𝐵 = 𝑧 / 𝑥𝐵
34 ssun2 4131 . . . . . . . . . . 11 {𝑧} ⊆ (𝑦 ∪ {𝑧})
35 vsnid 4621 . . . . . . . . . . 11 𝑧 ∈ {𝑧}
3634, 35sselii 3939 . . . . . . . . . 10 𝑧 ∈ (𝑦 ∪ {𝑧})
37 nfcsb1v 3878 . . . . . . . . . . . 12 𝑥𝑧 / 𝑥𝐵
3837nfel1 2921 . . . . . . . . . . 11 𝑥𝑧 / 𝑥𝐵 ∈ Fin
39 csbeq1a 3867 . . . . . . . . . . . 12 (𝑥 = 𝑧𝐵 = 𝑧 / 𝑥𝐵)
4039eleq1d 2822 . . . . . . . . . . 11 (𝑥 = 𝑧 → (𝐵 ∈ Fin ↔ 𝑧 / 𝑥𝐵 ∈ Fin))
4138, 40rspc 3567 . . . . . . . . . 10 (𝑧 ∈ (𝑦 ∪ {𝑧}) → (∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin → 𝑧 / 𝑥𝐵 ∈ Fin))
4236, 41ax-mp 5 . . . . . . . . 9 (∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin → 𝑧 / 𝑥𝐵 ∈ Fin)
4333, 42eqeltrid 2842 . . . . . . . 8 (∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin → 𝑥 ∈ {𝑧}𝐵 ∈ Fin)
44 unfi 9074 . . . . . . . 8 (( 𝑥𝑦 𝐵 ∈ Fin ∧ 𝑥 ∈ {𝑧}𝐵 ∈ Fin) → ( 𝑥𝑦 𝐵 𝑥 ∈ {𝑧}𝐵) ∈ Fin)
4543, 44sylan2 593 . . . . . . 7 (( 𝑥𝑦 𝐵 ∈ Fin ∧ ∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin) → ( 𝑥𝑦 𝐵 𝑥 ∈ {𝑧}𝐵) ∈ Fin)
4625, 45eqeltrid 2842 . . . . . 6 (( 𝑥𝑦 𝐵 ∈ Fin ∧ ∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin) → 𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin)
4746expcom 414 . . . . 5 (∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin → ( 𝑥𝑦 𝐵 ∈ Fin → 𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin))
4824, 47sylcom 30 . . . 4 ((∀𝑥𝑦 𝐵 ∈ Fin → 𝑥𝑦 𝐵 ∈ Fin) → (∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin → 𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin))
4948a1i 11 . . 3 (𝑦 ∈ Fin → ((∀𝑥𝑦 𝐵 ∈ Fin → 𝑥𝑦 𝐵 ∈ Fin) → (∀𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin → 𝑥 ∈ (𝑦 ∪ {𝑧})𝐵 ∈ Fin)))
506, 10, 14, 18, 20, 49findcard2 9066 . 2 (𝐴 ∈ Fin → (∀𝑥𝐴 𝐵 ∈ Fin → 𝑥𝐴 𝐵 ∈ Fin))
5150imp 407 1 ((𝐴 ∈ Fin ∧ ∀𝑥𝐴 𝐵 ∈ Fin) → 𝑥𝐴 𝐵 ∈ Fin)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 396   = wceq 1541  wcel 2106  wral 3062  csb 3853  cun 3906  wss 3908  c0 4280  {csn 4584   ciun 4952  Fincfn 8841
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 1913  ax-6 1971  ax-7 2011  ax-8 2108  ax-9 2116  ax-10 2137  ax-11 2154  ax-12 2171  ax-ext 2708  ax-sep 5254  ax-nul 5261  ax-pr 5382  ax-un 7664
This theorem depends on definitions:  df-bi 206  df-an 397  df-or 846  df-3or 1088  df-3an 1089  df-tru 1544  df-fal 1554  df-ex 1782  df-nf 1786  df-sb 2068  df-mo 2539  df-eu 2568  df-clab 2715  df-cleq 2729  df-clel 2815  df-nfc 2887  df-ne 2942  df-ral 3063  df-rex 3072  df-reu 3352  df-rab 3406  df-v 3445  df-sbc 3738  df-csb 3854  df-dif 3911  df-un 3913  df-in 3915  df-ss 3925  df-pss 3927  df-nul 4281  df-if 4485  df-pw 4560  df-sn 4585  df-pr 4587  df-op 4591  df-uni 4864  df-iun 4954  df-br 5104  df-opab 5166  df-tr 5221  df-id 5529  df-eprel 5535  df-po 5543  df-so 5544  df-fr 5586  df-we 5588  df-xp 5637  df-rel 5638  df-cnv 5639  df-co 5640  df-dm 5641  df-rn 5642  df-res 5643  df-ima 5644  df-ord 6318  df-on 6319  df-lim 6320  df-suc 6321  df-iota 6445  df-fun 6495  df-fn 6496  df-f 6497  df-f1 6498  df-fo 6499  df-f1o 6500  df-fv 6501  df-om 7795  df-en 8842  df-fin 8845
This theorem is referenced by:  unifi  9243  infssuni  9245  ixpfi  9251  ackbij1lem9  10122  ackbij1lem10  10123  fsuppmapnn0fiublem  13849  fsuppmapnn0fiub  13850  fsum2dlem  15614  fsumcom2  15618  fsumiun  15665  hashiun  15666  hash2iun  15667  ackbijnn  15672  fprod2dlem  15822  fprodcom2  15826  ablfaclem3  19824  pmatcoe1fsupp  22001  locfincmp  22828  txcmplem2  22944  alexsubALTlem3  23351  aannenlem1  25639  fsumvma  26512  numedglnl  27923  fsumiunle  31549  fedgmullem1  32137  poimirlem30  36039  fiphp3d  41044  hbt  41359  cnrefiisplem  43964
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