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Theorem txcld 21777
 Description: The product of two closed sets is closed in the product topology. (Contributed by Jeff Madsen, 2-Sep-2009.) (Revised by Mario Carneiro, 3-Sep-2015.)
Assertion
Ref Expression
txcld ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → (𝐴 × 𝐵) ∈ (Clsd‘(𝑅 ×t 𝑆)))

Proof of Theorem txcld
StepHypRef Expression
1 eqid 2825 . . . . 5 𝑅 = 𝑅
21cldss 21204 . . . 4 (𝐴 ∈ (Clsd‘𝑅) → 𝐴 𝑅)
3 eqid 2825 . . . . 5 𝑆 = 𝑆
43cldss 21204 . . . 4 (𝐵 ∈ (Clsd‘𝑆) → 𝐵 𝑆)
5 xpss12 5357 . . . 4 ((𝐴 𝑅𝐵 𝑆) → (𝐴 × 𝐵) ⊆ ( 𝑅 × 𝑆))
62, 4, 5syl2an 589 . . 3 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → (𝐴 × 𝐵) ⊆ ( 𝑅 × 𝑆))
7 cldrcl 21201 . . . 4 (𝐴 ∈ (Clsd‘𝑅) → 𝑅 ∈ Top)
8 cldrcl 21201 . . . 4 (𝐵 ∈ (Clsd‘𝑆) → 𝑆 ∈ Top)
91, 3txuni 21766 . . . 4 ((𝑅 ∈ Top ∧ 𝑆 ∈ Top) → ( 𝑅 × 𝑆) = (𝑅 ×t 𝑆))
107, 8, 9syl2an 589 . . 3 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → ( 𝑅 × 𝑆) = (𝑅 ×t 𝑆))
116, 10sseqtrd 3866 . 2 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → (𝐴 × 𝐵) ⊆ (𝑅 ×t 𝑆))
12 difxp 5799 . . . 4 (( 𝑅 × 𝑆) ∖ (𝐴 × 𝐵)) = ((( 𝑅𝐴) × 𝑆) ∪ ( 𝑅 × ( 𝑆𝐵)))
1310difeq1d 3954 . . . 4 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → (( 𝑅 × 𝑆) ∖ (𝐴 × 𝐵)) = ( (𝑅 ×t 𝑆) ∖ (𝐴 × 𝐵)))
1412, 13syl5eqr 2875 . . 3 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → ((( 𝑅𝐴) × 𝑆) ∪ ( 𝑅 × ( 𝑆𝐵))) = ( (𝑅 ×t 𝑆) ∖ (𝐴 × 𝐵)))
15 txtop 21743 . . . . 5 ((𝑅 ∈ Top ∧ 𝑆 ∈ Top) → (𝑅 ×t 𝑆) ∈ Top)
167, 8, 15syl2an 589 . . . 4 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → (𝑅 ×t 𝑆) ∈ Top)
177adantr 474 . . . . 5 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → 𝑅 ∈ Top)
188adantl 475 . . . . 5 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → 𝑆 ∈ Top)
191cldopn 21206 . . . . . 6 (𝐴 ∈ (Clsd‘𝑅) → ( 𝑅𝐴) ∈ 𝑅)
2019adantr 474 . . . . 5 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → ( 𝑅𝐴) ∈ 𝑅)
213topopn 21081 . . . . . 6 (𝑆 ∈ Top → 𝑆𝑆)
2218, 21syl 17 . . . . 5 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → 𝑆𝑆)
23 txopn 21776 . . . . 5 (((𝑅 ∈ Top ∧ 𝑆 ∈ Top) ∧ (( 𝑅𝐴) ∈ 𝑅 𝑆𝑆)) → (( 𝑅𝐴) × 𝑆) ∈ (𝑅 ×t 𝑆))
2417, 18, 20, 22, 23syl22anc 872 . . . 4 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → (( 𝑅𝐴) × 𝑆) ∈ (𝑅 ×t 𝑆))
251topopn 21081 . . . . . 6 (𝑅 ∈ Top → 𝑅𝑅)
2617, 25syl 17 . . . . 5 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → 𝑅𝑅)
273cldopn 21206 . . . . . 6 (𝐵 ∈ (Clsd‘𝑆) → ( 𝑆𝐵) ∈ 𝑆)
2827adantl 475 . . . . 5 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → ( 𝑆𝐵) ∈ 𝑆)
29 txopn 21776 . . . . 5 (((𝑅 ∈ Top ∧ 𝑆 ∈ Top) ∧ ( 𝑅𝑅 ∧ ( 𝑆𝐵) ∈ 𝑆)) → ( 𝑅 × ( 𝑆𝐵)) ∈ (𝑅 ×t 𝑆))
3017, 18, 26, 28, 29syl22anc 872 . . . 4 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → ( 𝑅 × ( 𝑆𝐵)) ∈ (𝑅 ×t 𝑆))
31 unopn 21078 . . . 4 (((𝑅 ×t 𝑆) ∈ Top ∧ (( 𝑅𝐴) × 𝑆) ∈ (𝑅 ×t 𝑆) ∧ ( 𝑅 × ( 𝑆𝐵)) ∈ (𝑅 ×t 𝑆)) → ((( 𝑅𝐴) × 𝑆) ∪ ( 𝑅 × ( 𝑆𝐵))) ∈ (𝑅 ×t 𝑆))
3216, 24, 30, 31syl3anc 1494 . . 3 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → ((( 𝑅𝐴) × 𝑆) ∪ ( 𝑅 × ( 𝑆𝐵))) ∈ (𝑅 ×t 𝑆))
3314, 32eqeltrrd 2907 . 2 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → ( (𝑅 ×t 𝑆) ∖ (𝐴 × 𝐵)) ∈ (𝑅 ×t 𝑆))
34 eqid 2825 . . . 4 (𝑅 ×t 𝑆) = (𝑅 ×t 𝑆)
3534iscld 21202 . . 3 ((𝑅 ×t 𝑆) ∈ Top → ((𝐴 × 𝐵) ∈ (Clsd‘(𝑅 ×t 𝑆)) ↔ ((𝐴 × 𝐵) ⊆ (𝑅 ×t 𝑆) ∧ ( (𝑅 ×t 𝑆) ∖ (𝐴 × 𝐵)) ∈ (𝑅 ×t 𝑆))))
3616, 35syl 17 . 2 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → ((𝐴 × 𝐵) ∈ (Clsd‘(𝑅 ×t 𝑆)) ↔ ((𝐴 × 𝐵) ⊆ (𝑅 ×t 𝑆) ∧ ( (𝑅 ×t 𝑆) ∖ (𝐴 × 𝐵)) ∈ (𝑅 ×t 𝑆))))
3711, 33, 36mpbir2and 704 1 ((𝐴 ∈ (Clsd‘𝑅) ∧ 𝐵 ∈ (Clsd‘𝑆)) → (𝐴 × 𝐵) ∈ (Clsd‘(𝑅 ×t 𝑆)))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 198   ∧ wa 386   = wceq 1656   ∈ wcel 2164   ∖ cdif 3795   ∪ cun 3796   ⊆ wss 3798  ∪ cuni 4658   × cxp 5340  ‘cfv 6123  (class class class)co 6905  Topctop 21068  Clsdccld 21191   ×t ctx 21734 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1894  ax-4 1908  ax-5 2009  ax-6 2075  ax-7 2112  ax-8 2166  ax-9 2173  ax-10 2192  ax-11 2207  ax-12 2220  ax-13 2389  ax-ext 2803  ax-sep 5005  ax-nul 5013  ax-pow 5065  ax-pr 5127  ax-un 7209 This theorem depends on definitions:  df-bi 199  df-an 387  df-or 879  df-3an 1113  df-tru 1660  df-ex 1879  df-nf 1883  df-sb 2068  df-mo 2605  df-eu 2640  df-clab 2812  df-cleq 2818  df-clel 2821  df-nfc 2958  df-ne 3000  df-ral 3122  df-rex 3123  df-rab 3126  df-v 3416  df-sbc 3663  df-csb 3758  df-dif 3801  df-un 3803  df-in 3805  df-ss 3812  df-nul 4145  df-if 4307  df-pw 4380  df-sn 4398  df-pr 4400  df-op 4404  df-uni 4659  df-iun 4742  df-br 4874  df-opab 4936  df-mpt 4953  df-id 5250  df-xp 5348  df-rel 5349  df-cnv 5350  df-co 5351  df-dm 5352  df-rn 5353  df-res 5354  df-ima 5355  df-iota 6086  df-fun 6125  df-fn 6126  df-f 6127  df-fv 6131  df-ov 6908  df-oprab 6909  df-mpt2 6910  df-1st 7428  df-2nd 7429  df-topgen 16457  df-top 21069  df-topon 21086  df-bases 21121  df-cld 21194  df-tx 21736 This theorem is referenced by:  txcls  21778  cnmpt2pc  23097  sxbrsigalem3  30868
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