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Theorem iuncld 23069
Description: A finite indexed union of closed sets is closed. (Contributed by Mario Carneiro, 19-Sep-2015.)
Hypothesis
Ref Expression
clscld.1 𝑋 = 𝐽
Assertion
Ref Expression
iuncld ((𝐽 ∈ Top ∧ 𝐴 ∈ Fin ∧ ∀𝑥𝐴 𝐵 ∈ (Clsd‘𝐽)) → 𝑥𝐴 𝐵 ∈ (Clsd‘𝐽))
Distinct variable groups:   𝑥,𝐽   𝑥,𝑋   𝑥,𝐴
Allowed substitution hint:   𝐵(𝑥)

Proof of Theorem iuncld
StepHypRef Expression
1 difin 4278 . . . 4 (𝑋 ∖ (𝑋 𝑥𝐴 (𝑋𝐵))) = (𝑋 𝑥𝐴 (𝑋𝐵))
2 iundif2 5079 . . . 4 𝑥𝐴 (𝑋 ∖ (𝑋𝐵)) = (𝑋 𝑥𝐴 (𝑋𝐵))
31, 2eqtr4i 2766 . . 3 (𝑋 ∖ (𝑋 𝑥𝐴 (𝑋𝐵))) = 𝑥𝐴 (𝑋 ∖ (𝑋𝐵))
4 clscld.1 . . . . . . . 8 𝑋 = 𝐽
54cldss 23053 . . . . . . 7 (𝐵 ∈ (Clsd‘𝐽) → 𝐵𝑋)
6 dfss4 4275 . . . . . . 7 (𝐵𝑋 ↔ (𝑋 ∖ (𝑋𝐵)) = 𝐵)
75, 6sylib 218 . . . . . 6 (𝐵 ∈ (Clsd‘𝐽) → (𝑋 ∖ (𝑋𝐵)) = 𝐵)
87ralimi 3081 . . . . 5 (∀𝑥𝐴 𝐵 ∈ (Clsd‘𝐽) → ∀𝑥𝐴 (𝑋 ∖ (𝑋𝐵)) = 𝐵)
983ad2ant3 1134 . . . 4 ((𝐽 ∈ Top ∧ 𝐴 ∈ Fin ∧ ∀𝑥𝐴 𝐵 ∈ (Clsd‘𝐽)) → ∀𝑥𝐴 (𝑋 ∖ (𝑋𝐵)) = 𝐵)
10 iuneq2 5016 . . . 4 (∀𝑥𝐴 (𝑋 ∖ (𝑋𝐵)) = 𝐵 𝑥𝐴 (𝑋 ∖ (𝑋𝐵)) = 𝑥𝐴 𝐵)
119, 10syl 17 . . 3 ((𝐽 ∈ Top ∧ 𝐴 ∈ Fin ∧ ∀𝑥𝐴 𝐵 ∈ (Clsd‘𝐽)) → 𝑥𝐴 (𝑋 ∖ (𝑋𝐵)) = 𝑥𝐴 𝐵)
123, 11eqtrid 2787 . 2 ((𝐽 ∈ Top ∧ 𝐴 ∈ Fin ∧ ∀𝑥𝐴 𝐵 ∈ (Clsd‘𝐽)) → (𝑋 ∖ (𝑋 𝑥𝐴 (𝑋𝐵))) = 𝑥𝐴 𝐵)
13 simp1 1135 . . 3 ((𝐽 ∈ Top ∧ 𝐴 ∈ Fin ∧ ∀𝑥𝐴 𝐵 ∈ (Clsd‘𝐽)) → 𝐽 ∈ Top)
144cldopn 23055 . . . . 5 (𝐵 ∈ (Clsd‘𝐽) → (𝑋𝐵) ∈ 𝐽)
1514ralimi 3081 . . . 4 (∀𝑥𝐴 𝐵 ∈ (Clsd‘𝐽) → ∀𝑥𝐴 (𝑋𝐵) ∈ 𝐽)
164riinopn 22930 . . . 4 ((𝐽 ∈ Top ∧ 𝐴 ∈ Fin ∧ ∀𝑥𝐴 (𝑋𝐵) ∈ 𝐽) → (𝑋 𝑥𝐴 (𝑋𝐵)) ∈ 𝐽)
1715, 16syl3an3 1164 . . 3 ((𝐽 ∈ Top ∧ 𝐴 ∈ Fin ∧ ∀𝑥𝐴 𝐵 ∈ (Clsd‘𝐽)) → (𝑋 𝑥𝐴 (𝑋𝐵)) ∈ 𝐽)
184opncld 23057 . . 3 ((𝐽 ∈ Top ∧ (𝑋 𝑥𝐴 (𝑋𝐵)) ∈ 𝐽) → (𝑋 ∖ (𝑋 𝑥𝐴 (𝑋𝐵))) ∈ (Clsd‘𝐽))
1913, 17, 18syl2anc 584 . 2 ((𝐽 ∈ Top ∧ 𝐴 ∈ Fin ∧ ∀𝑥𝐴 𝐵 ∈ (Clsd‘𝐽)) → (𝑋 ∖ (𝑋 𝑥𝐴 (𝑋𝐵))) ∈ (Clsd‘𝐽))
2012, 19eqeltrrd 2840 1 ((𝐽 ∈ Top ∧ 𝐴 ∈ Fin ∧ ∀𝑥𝐴 𝐵 ∈ (Clsd‘𝐽)) → 𝑥𝐴 𝐵 ∈ (Clsd‘𝐽))
Colors of variables: wff setvar class
Syntax hints:  wi 4  w3a 1086   = wceq 1537  wcel 2106  wral 3059  cdif 3960  cin 3962  wss 3963   cuni 4912   ciun 4996   ciin 4997  cfv 6563  Fincfn 8984  Topctop 22915  Clsdccld 23040
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1792  ax-4 1806  ax-5 1908  ax-6 1965  ax-7 2005  ax-8 2108  ax-9 2116  ax-10 2139  ax-11 2155  ax-12 2175  ax-ext 2706  ax-sep 5302  ax-nul 5312  ax-pow 5371  ax-pr 5438  ax-un 7754
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3or 1087  df-3an 1088  df-tru 1540  df-fal 1550  df-ex 1777  df-nf 1781  df-sb 2063  df-mo 2538  df-eu 2567  df-clab 2713  df-cleq 2727  df-clel 2814  df-nfc 2890  df-ne 2939  df-ral 3060  df-rex 3069  df-reu 3379  df-rab 3434  df-v 3480  df-sbc 3792  df-dif 3966  df-un 3968  df-in 3970  df-ss 3980  df-pss 3983  df-nul 4340  df-if 4532  df-pw 4607  df-sn 4632  df-pr 4634  df-op 4638  df-uni 4913  df-int 4952  df-iun 4998  df-iin 4999  df-br 5149  df-opab 5211  df-mpt 5232  df-tr 5266  df-id 5583  df-eprel 5589  df-po 5597  df-so 5598  df-fr 5641  df-we 5643  df-xp 5695  df-rel 5696  df-cnv 5697  df-co 5698  df-dm 5699  df-rn 5700  df-res 5701  df-ima 5702  df-ord 6389  df-on 6390  df-lim 6391  df-suc 6392  df-iota 6516  df-fun 6565  df-fn 6566  df-f 6567  df-f1 6568  df-fo 6569  df-f1o 6570  df-fv 6571  df-om 7888  df-1st 8013  df-2nd 8014  df-1o 8505  df-2o 8506  df-en 8985  df-dom 8986  df-fin 8988  df-top 22916  df-cld 23043
This theorem is referenced by:  unicld  23070  t1ficld  23351  mblfinlem1  37644  mblfinlem2  37645
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