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Theorem clscld 20661
 Description: The closure of a subset of a topology's underlying set is closed. (Contributed by NM, 4-Oct-2006.)
Hypothesis
Ref Expression
clscld.1 𝑋 = 𝐽
Assertion
Ref Expression
clscld ((𝐽 ∈ Top ∧ 𝑆𝑋) → ((cls‘𝐽)‘𝑆) ∈ (Clsd‘𝐽))

Proof of Theorem clscld
Dummy variable 𝑥 is distinct from all other variables.
StepHypRef Expression
1 clscld.1 . . 3 𝑋 = 𝐽
21clsval 20651 . 2 ((𝐽 ∈ Top ∧ 𝑆𝑋) → ((cls‘𝐽)‘𝑆) = {𝑥 ∈ (Clsd‘𝐽) ∣ 𝑆𝑥})
31topcld 20649 . . . . . 6 (𝐽 ∈ Top → 𝑋 ∈ (Clsd‘𝐽))
43anim1i 590 . . . . 5 ((𝐽 ∈ Top ∧ 𝑆𝑋) → (𝑋 ∈ (Clsd‘𝐽) ∧ 𝑆𝑋))
5 sseq2 3590 . . . . . 6 (𝑥 = 𝑋 → (𝑆𝑥𝑆𝑋))
65elrab 3331 . . . . 5 (𝑋 ∈ {𝑥 ∈ (Clsd‘𝐽) ∣ 𝑆𝑥} ↔ (𝑋 ∈ (Clsd‘𝐽) ∧ 𝑆𝑋))
74, 6sylibr 223 . . . 4 ((𝐽 ∈ Top ∧ 𝑆𝑋) → 𝑋 ∈ {𝑥 ∈ (Clsd‘𝐽) ∣ 𝑆𝑥})
8 ne0i 3880 . . . 4 (𝑋 ∈ {𝑥 ∈ (Clsd‘𝐽) ∣ 𝑆𝑥} → {𝑥 ∈ (Clsd‘𝐽) ∣ 𝑆𝑥} ≠ ∅)
97, 8syl 17 . . 3 ((𝐽 ∈ Top ∧ 𝑆𝑋) → {𝑥 ∈ (Clsd‘𝐽) ∣ 𝑆𝑥} ≠ ∅)
10 ssrab2 3650 . . 3 {𝑥 ∈ (Clsd‘𝐽) ∣ 𝑆𝑥} ⊆ (Clsd‘𝐽)
11 intcld 20654 . . 3 (({𝑥 ∈ (Clsd‘𝐽) ∣ 𝑆𝑥} ≠ ∅ ∧ {𝑥 ∈ (Clsd‘𝐽) ∣ 𝑆𝑥} ⊆ (Clsd‘𝐽)) → {𝑥 ∈ (Clsd‘𝐽) ∣ 𝑆𝑥} ∈ (Clsd‘𝐽))
129, 10, 11sylancl 693 . 2 ((𝐽 ∈ Top ∧ 𝑆𝑋) → {𝑥 ∈ (Clsd‘𝐽) ∣ 𝑆𝑥} ∈ (Clsd‘𝐽))
132, 12eqeltrd 2688 1 ((𝐽 ∈ Top ∧ 𝑆𝑋) → ((cls‘𝐽)‘𝑆) ∈ (Clsd‘𝐽))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ∧ wa 383   = wceq 1475   ∈ wcel 1977   ≠ wne 2780  {crab 2900   ⊆ wss 3540  ∅c0 3874  ∪ cuni 4372  ∩ cint 4410  ‘cfv 5804  Topctop 20517  Clsdccld 20630  clsccl 20632 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-8 1979  ax-9 1986  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590  ax-rep 4699  ax-sep 4709  ax-nul 4717  ax-pow 4769  ax-pr 4833  ax-un 6847 This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-3an 1033  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-eu 2462  df-mo 2463  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-ne 2782  df-ral 2901  df-rex 2902  df-reu 2903  df-rab 2905  df-v 3175  df-sbc 3403  df-csb 3500  df-dif 3543  df-un 3545  df-in 3547  df-ss 3554  df-nul 3875  df-if 4037  df-pw 4110  df-sn 4126  df-pr 4128  df-op 4132  df-uni 4373  df-int 4411  df-iun 4457  df-iin 4458  df-br 4584  df-opab 4644  df-mpt 4645  df-id 4953  df-xp 5044  df-rel 5045  df-cnv 5046  df-co 5047  df-dm 5048  df-rn 5049  df-res 5050  df-ima 5051  df-iota 5768  df-fun 5806  df-fn 5807  df-f 5808  df-f1 5809  df-fo 5810  df-f1o 5811  df-fv 5812  df-top 20521  df-cld 20633  df-cls 20635 This theorem is referenced by:  clsf  20662  clsss3  20673  iscld3  20678  clsidm  20681  restcls  20795  cncls2i  20884  nrmsep  20971  lpcls  20978  regsep2  20990  hauscmplem  21019  hausllycmp  21107  txcls  21217  ptclsg  21228  regr1lem  21352  kqreglem1  21354  kqreglem2  21355  kqnrmlem1  21356  kqnrmlem2  21357  fclscmpi  21643  tgptsmscld  21764  cnllycmp  22563  clsocv  22857  cmpcmet  22924  cncmet  22927  limcnlp  23448  clsun  31493  cldregopn  31496  heibor1lem  32778
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