Theorem nrmsep2 22842

Description: In a normal space, any two disjoint closed sets have the property that each one is a subset of an open set whose closure is disjoint from the other. (Contributed by Jeff Hankins, 1-Feb-2010.) (Revised by Mario Carneiro, 24-Aug-2015.)

Assertion

Ref	Expression
nrmsep2	⊢ ((𝐽 ∈ Nrm ∧ (𝐶 ∈ (Clsd‘𝐽) ∧ 𝐷 ∈ (Clsd‘𝐽) ∧ (𝐶 ∩ 𝐷) = ∅)) → ∃𝑥 ∈ 𝐽 (𝐶 ⊆ 𝑥 ∧ (((cls‘𝐽)‘𝑥) ∩ 𝐷) = ∅))

Distinct variable groups:   𝑥,𝐶   𝑥,𝐷   𝑥,𝐽

Proof of Theorem nrmsep2

Step	Hyp	Ref	Expression
1		simpl 484	. . 3 ⊢ ((𝐽 ∈ Nrm ∧ (𝐶 ∈ (Clsd‘𝐽) ∧ 𝐷 ∈ (Clsd‘𝐽) ∧ (𝐶 ∩ 𝐷) = ∅)) → 𝐽 ∈ Nrm)
2		simpr2 1196	. . . 4 ⊢ ((𝐽 ∈ Nrm ∧ (𝐶 ∈ (Clsd‘𝐽) ∧ 𝐷 ∈ (Clsd‘𝐽) ∧ (𝐶 ∩ 𝐷) = ∅)) → 𝐷 ∈ (Clsd‘𝐽))
3		eqid 2733	. . . . 5 ⊢ ∪ 𝐽 = ∪ 𝐽
4	3	cldopn 22517	. . . 4 ⊢ (𝐷 ∈ (Clsd‘𝐽) → (∪ 𝐽 ∖ 𝐷) ∈ 𝐽)
5	2, 4	syl 17	. . 3 ⊢ ((𝐽 ∈ Nrm ∧ (𝐶 ∈ (Clsd‘𝐽) ∧ 𝐷 ∈ (Clsd‘𝐽) ∧ (𝐶 ∩ 𝐷) = ∅)) → (∪ 𝐽 ∖ 𝐷) ∈ 𝐽)
6		simpr1 1195	. . 3 ⊢ ((𝐽 ∈ Nrm ∧ (𝐶 ∈ (Clsd‘𝐽) ∧ 𝐷 ∈ (Clsd‘𝐽) ∧ (𝐶 ∩ 𝐷) = ∅)) → 𝐶 ∈ (Clsd‘𝐽))
7		simpr3 1197	. . . 4 ⊢ ((𝐽 ∈ Nrm ∧ (𝐶 ∈ (Clsd‘𝐽) ∧ 𝐷 ∈ (Clsd‘𝐽) ∧ (𝐶 ∩ 𝐷) = ∅)) → (𝐶 ∩ 𝐷) = ∅)
8	3	cldss 22515	. . . . 5 ⊢ (𝐶 ∈ (Clsd‘𝐽) → 𝐶 ⊆ ∪ 𝐽)
9		reldisj 4450	. . . . 5 ⊢ (𝐶 ⊆ ∪ 𝐽 → ((𝐶 ∩ 𝐷) = ∅ ↔ 𝐶 ⊆ (∪ 𝐽 ∖ 𝐷)))
10	6, 8, 9	3syl 18	. . . 4 ⊢ ((𝐽 ∈ Nrm ∧ (𝐶 ∈ (Clsd‘𝐽) ∧ 𝐷 ∈ (Clsd‘𝐽) ∧ (𝐶 ∩ 𝐷) = ∅)) → ((𝐶 ∩ 𝐷) = ∅ ↔ 𝐶 ⊆ (∪ 𝐽 ∖ 𝐷)))
11	7, 10	mpbid 231	. . 3 ⊢ ((𝐽 ∈ Nrm ∧ (𝐶 ∈ (Clsd‘𝐽) ∧ 𝐷 ∈ (Clsd‘𝐽) ∧ (𝐶 ∩ 𝐷) = ∅)) → 𝐶 ⊆ (∪ 𝐽 ∖ 𝐷))
12		nrmsep3 22841	. . 3 ⊢ ((𝐽 ∈ Nrm ∧ ((∪ 𝐽 ∖ 𝐷) ∈ 𝐽 ∧ 𝐶 ∈ (Clsd‘𝐽) ∧ 𝐶 ⊆ (∪ 𝐽 ∖ 𝐷))) → ∃𝑥 ∈ 𝐽 (𝐶 ⊆ 𝑥 ∧ ((cls‘𝐽)‘𝑥) ⊆ (∪ 𝐽 ∖ 𝐷)))
13	1, 5, 6, 11, 12	syl13anc 1373	. 2 ⊢ ((𝐽 ∈ Nrm ∧ (𝐶 ∈ (Clsd‘𝐽) ∧ 𝐷 ∈ (Clsd‘𝐽) ∧ (𝐶 ∩ 𝐷) = ∅)) → ∃𝑥 ∈ 𝐽 (𝐶 ⊆ 𝑥 ∧ ((cls‘𝐽)‘𝑥) ⊆ (∪ 𝐽 ∖ 𝐷)))
14		ssdifin0 4484	. . . 4 ⊢ (((cls‘𝐽)‘𝑥) ⊆ (∪ 𝐽 ∖ 𝐷) → (((cls‘𝐽)‘𝑥) ∩ 𝐷) = ∅)
15	14	anim2i 618	. . 3 ⊢ ((𝐶 ⊆ 𝑥 ∧ ((cls‘𝐽)‘𝑥) ⊆ (∪ 𝐽 ∖ 𝐷)) → (𝐶 ⊆ 𝑥 ∧ (((cls‘𝐽)‘𝑥) ∩ 𝐷) = ∅))
16	15	reximi 3085	. 2 ⊢ (∃𝑥 ∈ 𝐽 (𝐶 ⊆ 𝑥 ∧ ((cls‘𝐽)‘𝑥) ⊆ (∪ 𝐽 ∖ 𝐷)) → ∃𝑥 ∈ 𝐽 (𝐶 ⊆ 𝑥 ∧ (((cls‘𝐽)‘𝑥) ∩ 𝐷) = ∅))
17	13, 16	syl 17	1 ⊢ ((𝐽 ∈ Nrm ∧ (𝐶 ∈ (Clsd‘𝐽) ∧ 𝐷 ∈ (Clsd‘𝐽) ∧ (𝐶 ∩ 𝐷) = ∅)) → ∃𝑥 ∈ 𝐽 (𝐶 ⊆ 𝑥 ∧ (((cls‘𝐽)‘𝑥) ∩ 𝐷) = ∅))

Syntax hints:   → wi 4   ↔ wb 205   ∧ wa 397   ∧ w3a 1088   = wceq 1542   ∈ wcel 2107  ∃wrex 3071   ∖ cdif 3944   ∩ cin 3946   ⊆ wss 3947  ∅c0 4321  ∪ cuni 4907  ‘cfv 6540  Clsdccld 22502  clsccl 22504  Nrmcnrm 22796

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1798  ax-4 1812  ax-5 1914  ax-6 1972  ax-7 2012  ax-8 2109  ax-9 2117  ax-10 2138  ax-11 2155  ax-12 2172  ax-ext 2704  ax-sep 5298  ax-nul 5305  ax-pow 5362  ax-pr 5426  ax-un 7720

This theorem depends on definitions:  df-bi 206  df-an 398  df-or 847  df-3an 1090  df-tru 1545  df-fal 1555  df-ex 1783  df-nf 1787  df-sb 2069  df-mo 2535  df-eu 2564  df-clab 2711  df-cleq 2725  df-clel 2811  df-nfc 2886  df-ral 3063  df-rex 3072  df-rab 3434  df-v 3477  df-dif 3950  df-un 3952  df-in 3954  df-ss 3964  df-nul 4322  df-if 4528  df-pw 4603  df-sn 4628  df-pr 4630  df-op 4634  df-uni 4908  df-br 5148  df-opab 5210  df-mpt 5231  df-id 5573  df-xp 5681  df-rel 5682  df-cnv 5683  df-co 5684  df-dm 5685  df-iota 6492  df-fun 6542  df-fn 6543  df-fv 6548  df-top 22378  df-cld 22505  df-nrm 22803

This theorem is referenced by:  nrmsep  22843  isnrm2  22844