Theorem neifil 23765

Description: The neighborhoods of a nonempty set is a filter. Example 2 of [BourbakiTop1] p. I.36. (Contributed by FL, 18-Sep-2007.) (Revised by Mario Carneiro, 23-Aug-2015.)

Assertion

Ref	Expression
neifil	⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝑆 ≠ ∅) → ((nei‘𝐽)‘𝑆) ∈ (Fil‘𝑋))

Proof of Theorem neifil

Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		toponuni 22799	. . . . . . . 8 ⊢ (𝐽 ∈ (TopOn‘𝑋) → 𝑋 = ∪ 𝐽)
2	1	adantr 480	. . . . . . 7 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) → 𝑋 = ∪ 𝐽)
3		topontop 22798	. . . . . . . . 9 ⊢ (𝐽 ∈ (TopOn‘𝑋) → 𝐽 ∈ Top)
4	3	adantr 480	. . . . . . . 8 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) → 𝐽 ∈ Top)
5		simpr 484	. . . . . . . . 9 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) → 𝑆 ⊆ 𝑋)
6	5, 2	sseqtrd 3972	. . . . . . . 8 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) → 𝑆 ⊆ ∪ 𝐽)
7		eqid 2729	. . . . . . . . 9 ⊢ ∪ 𝐽 = ∪ 𝐽
8	7	neiuni 23007	. . . . . . . 8 ⊢ ((𝐽 ∈ Top ∧ 𝑆 ⊆ ∪ 𝐽) → ∪ 𝐽 = ∪ ((nei‘𝐽)‘𝑆))
9	4, 6, 8	syl2anc 584	. . . . . . 7 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) → ∪ 𝐽 = ∪ ((nei‘𝐽)‘𝑆))
10	2, 9	eqtrd 2764	. . . . . 6 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) → 𝑋 = ∪ ((nei‘𝐽)‘𝑆))
11		eqimss2 3995	. . . . . 6 ⊢ (𝑋 = ∪ ((nei‘𝐽)‘𝑆) → ∪ ((nei‘𝐽)‘𝑆) ⊆ 𝑋)
12	10, 11	syl 17	. . . . 5 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) → ∪ ((nei‘𝐽)‘𝑆) ⊆ 𝑋)
13		sspwuni 5049	. . . . 5 ⊢ (((nei‘𝐽)‘𝑆) ⊆ 𝒫 𝑋 ↔ ∪ ((nei‘𝐽)‘𝑆) ⊆ 𝑋)
14	12, 13	sylibr 234	. . . 4 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) → ((nei‘𝐽)‘𝑆) ⊆ 𝒫 𝑋)
15	14	3adant3 1132	. . 3 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝑆 ≠ ∅) → ((nei‘𝐽)‘𝑆) ⊆ 𝒫 𝑋)
16		0nnei 22997	. . . . 5 ⊢ ((𝐽 ∈ Top ∧ 𝑆 ≠ ∅) → ¬ ∅ ∈ ((nei‘𝐽)‘𝑆))
17	3, 16	sylan 580	. . . 4 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ≠ ∅) → ¬ ∅ ∈ ((nei‘𝐽)‘𝑆))
18	17	3adant2 1131	. . 3 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝑆 ≠ ∅) → ¬ ∅ ∈ ((nei‘𝐽)‘𝑆))
19	7	tpnei 23006	. . . . . . 7 ⊢ (𝐽 ∈ Top → (𝑆 ⊆ ∪ 𝐽 ↔ ∪ 𝐽 ∈ ((nei‘𝐽)‘𝑆)))
20	19	biimpa 476	. . . . . 6 ⊢ ((𝐽 ∈ Top ∧ 𝑆 ⊆ ∪ 𝐽) → ∪ 𝐽 ∈ ((nei‘𝐽)‘𝑆))
21	4, 6, 20	syl2anc 584	. . . . 5 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) → ∪ 𝐽 ∈ ((nei‘𝐽)‘𝑆))
22	2, 21	eqeltrd 2828	. . . 4 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) → 𝑋 ∈ ((nei‘𝐽)‘𝑆))
23	22	3adant3 1132	. . 3 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝑆 ≠ ∅) → 𝑋 ∈ ((nei‘𝐽)‘𝑆))
24	15, 18, 23	3jca 1128	. 2 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝑆 ≠ ∅) → (((nei‘𝐽)‘𝑆) ⊆ 𝒫 𝑋 ∧ ¬ ∅ ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑋 ∈ ((nei‘𝐽)‘𝑆)))
25		elpwi 4558	. . . . 5 ⊢ (𝑥 ∈ 𝒫 𝑋 → 𝑥 ⊆ 𝑋)
26	4	ad2antrr 726	. . . . . . 7 ⊢ ((((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) ∧ 𝑥 ⊆ 𝑋) ∧ (𝑦 ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑦 ⊆ 𝑥)) → 𝐽 ∈ Top)
27		simprl 770	. . . . . . 7 ⊢ ((((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) ∧ 𝑥 ⊆ 𝑋) ∧ (𝑦 ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑦 ⊆ 𝑥)) → 𝑦 ∈ ((nei‘𝐽)‘𝑆))
28		simprr 772	. . . . . . 7 ⊢ ((((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) ∧ 𝑥 ⊆ 𝑋) ∧ (𝑦 ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑦 ⊆ 𝑥)) → 𝑦 ⊆ 𝑥)
29		simplr 768	. . . . . . . 8 ⊢ ((((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) ∧ 𝑥 ⊆ 𝑋) ∧ (𝑦 ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑦 ⊆ 𝑥)) → 𝑥 ⊆ 𝑋)
30	2	ad2antrr 726	. . . . . . . 8 ⊢ ((((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) ∧ 𝑥 ⊆ 𝑋) ∧ (𝑦 ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑦 ⊆ 𝑥)) → 𝑋 = ∪ 𝐽)
31	29, 30	sseqtrd 3972	. . . . . . 7 ⊢ ((((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) ∧ 𝑥 ⊆ 𝑋) ∧ (𝑦 ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑦 ⊆ 𝑥)) → 𝑥 ⊆ ∪ 𝐽)
32	7	ssnei2 23001	. . . . . . 7 ⊢ (((𝐽 ∈ Top ∧ 𝑦 ∈ ((nei‘𝐽)‘𝑆)) ∧ (𝑦 ⊆ 𝑥 ∧ 𝑥 ⊆ ∪ 𝐽)) → 𝑥 ∈ ((nei‘𝐽)‘𝑆))
33	26, 27, 28, 31, 32	syl22anc 838	. . . . . 6 ⊢ ((((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) ∧ 𝑥 ⊆ 𝑋) ∧ (𝑦 ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑦 ⊆ 𝑥)) → 𝑥 ∈ ((nei‘𝐽)‘𝑆))
34	33	rexlimdvaa 3131	. . . . 5 ⊢ (((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) ∧ 𝑥 ⊆ 𝑋) → (∃𝑦 ∈ ((nei‘𝐽)‘𝑆)𝑦 ⊆ 𝑥 → 𝑥 ∈ ((nei‘𝐽)‘𝑆)))
35	25, 34	sylan2 593	. . . 4 ⊢ (((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) ∧ 𝑥 ∈ 𝒫 𝑋) → (∃𝑦 ∈ ((nei‘𝐽)‘𝑆)𝑦 ⊆ 𝑥 → 𝑥 ∈ ((nei‘𝐽)‘𝑆)))
36	35	ralrimiva 3121	. . 3 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋) → ∀𝑥 ∈ 𝒫 𝑋(∃𝑦 ∈ ((nei‘𝐽)‘𝑆)𝑦 ⊆ 𝑥 → 𝑥 ∈ ((nei‘𝐽)‘𝑆)))
37	36	3adant3 1132	. 2 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝑆 ≠ ∅) → ∀𝑥 ∈ 𝒫 𝑋(∃𝑦 ∈ ((nei‘𝐽)‘𝑆)𝑦 ⊆ 𝑥 → 𝑥 ∈ ((nei‘𝐽)‘𝑆)))
38		innei 23010	. . . . . 6 ⊢ ((𝐽 ∈ Top ∧ 𝑥 ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑦 ∈ ((nei‘𝐽)‘𝑆)) → (𝑥 ∩ 𝑦) ∈ ((nei‘𝐽)‘𝑆))
39	38	3expib 1122	. . . . 5 ⊢ (𝐽 ∈ Top → ((𝑥 ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑦 ∈ ((nei‘𝐽)‘𝑆)) → (𝑥 ∩ 𝑦) ∈ ((nei‘𝐽)‘𝑆)))
40	3, 39	syl 17	. . . 4 ⊢ (𝐽 ∈ (TopOn‘𝑋) → ((𝑥 ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑦 ∈ ((nei‘𝐽)‘𝑆)) → (𝑥 ∩ 𝑦) ∈ ((nei‘𝐽)‘𝑆)))
41	40	3ad2ant1 1133	. . 3 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝑆 ≠ ∅) → ((𝑥 ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑦 ∈ ((nei‘𝐽)‘𝑆)) → (𝑥 ∩ 𝑦) ∈ ((nei‘𝐽)‘𝑆)))
42	41	ralrimivv 3170	. 2 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝑆 ≠ ∅) → ∀𝑥 ∈ ((nei‘𝐽)‘𝑆)∀𝑦 ∈ ((nei‘𝐽)‘𝑆)(𝑥 ∩ 𝑦) ∈ ((nei‘𝐽)‘𝑆))
43		isfil2 23741	. 2 ⊢ (((nei‘𝐽)‘𝑆) ∈ (Fil‘𝑋) ↔ ((((nei‘𝐽)‘𝑆) ⊆ 𝒫 𝑋 ∧ ¬ ∅ ∈ ((nei‘𝐽)‘𝑆) ∧ 𝑋 ∈ ((nei‘𝐽)‘𝑆)) ∧ ∀𝑥 ∈ 𝒫 𝑋(∃𝑦 ∈ ((nei‘𝐽)‘𝑆)𝑦 ⊆ 𝑥 → 𝑥 ∈ ((nei‘𝐽)‘𝑆)) ∧ ∀𝑥 ∈ ((nei‘𝐽)‘𝑆)∀𝑦 ∈ ((nei‘𝐽)‘𝑆)(𝑥 ∩ 𝑦) ∈ ((nei‘𝐽)‘𝑆)))
44	24, 37, 42, 43	syl3anbrc 1344	1 ⊢ ((𝐽 ∈ (TopOn‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝑆 ≠ ∅) → ((nei‘𝐽)‘𝑆) ∈ (Fil‘𝑋))

Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 395   ∧ w3a 1086   = wceq 1540   ∈ wcel 2109   ≠ wne 2925  ∀wral 3044  ∃wrex 3053   ∩ cin 3902   ⊆ wss 3903  ∅c0 4284  𝒫 cpw 4551  ∪ cuni 4858  ‘cfv 6482  Topctop 22778  TopOnctopon 22795  neicnei 22982  Filcfil 23730

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1910  ax-6 1967  ax-7 2008  ax-8 2111  ax-9 2119  ax-10 2142  ax-11 2158  ax-12 2178  ax-ext 2701  ax-rep 5218  ax-sep 5235  ax-nul 5245  ax-pow 5304  ax-pr 5371  ax-un 7671

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3an 1088  df-tru 1543  df-fal 1553  df-ex 1780  df-nf 1784  df-sb 2066  df-mo 2533  df-eu 2562  df-clab 2708  df-cleq 2721  df-clel 2803  df-nfc 2878  df-ne 2926  df-nel 3030  df-ral 3045  df-rex 3054  df-reu 3344  df-rab 3395  df-v 3438  df-sbc 3743  df-csb 3852  df-dif 3906  df-un 3908  df-in 3910  df-ss 3920  df-nul 4285  df-if 4477  df-pw 4553  df-sn 4578  df-pr 4580  df-op 4584  df-uni 4859  df-iun 4943  df-br 5093  df-opab 5155  df-mpt 5174  df-id 5514  df-xp 5625  df-rel 5626  df-cnv 5627  df-co 5628  df-dm 5629  df-rn 5630  df-res 5631  df-ima 5632  df-iota 6438  df-fun 6484  df-fn 6485  df-f 6486  df-f1 6487  df-fo 6488  df-f1o 6489  df-fv 6490  df-fbas 21258  df-top 22779  df-topon 22796  df-nei 22983  df-fil 23731

This theorem is referenced by:  trnei  23777  neiflim  23859  hausflim  23866  flimcf  23867  flimclslem  23869  cnpflf2  23885  cnpflf  23886  fclsfnflim  23912  neipcfilu  24181