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Theorem eltg3 21137
Description: Membership in a topology generated by a basis. (Contributed by NM, 15-Jul-2006.) (Proof shortened by Mario Carneiro, 30-Aug-2015.)
Assertion
Ref Expression
eltg3 (𝐵𝑉 → (𝐴 ∈ (topGen‘𝐵) ↔ ∃𝑥(𝑥𝐵𝐴 = 𝑥)))
Distinct variable groups:   𝑥,𝐴   𝑥,𝐵   𝑥,𝑉

Proof of Theorem eltg3
StepHypRef Expression
1 elfvdm 6465 . . . 4 (𝐴 ∈ (topGen‘𝐵) → 𝐵 ∈ dom topGen)
2 inex1g 5026 . . . 4 (𝐵 ∈ dom topGen → (𝐵 ∩ 𝒫 𝐴) ∈ V)
31, 2syl 17 . . 3 (𝐴 ∈ (topGen‘𝐵) → (𝐵 ∩ 𝒫 𝐴) ∈ V)
4 eltg4i 21135 . . 3 (𝐴 ∈ (topGen‘𝐵) → 𝐴 = (𝐵 ∩ 𝒫 𝐴))
5 inss1 4057 . . . . . . 7 (𝐵 ∩ 𝒫 𝐴) ⊆ 𝐵
6 sseq1 3851 . . . . . . 7 (𝑥 = (𝐵 ∩ 𝒫 𝐴) → (𝑥𝐵 ↔ (𝐵 ∩ 𝒫 𝐴) ⊆ 𝐵))
75, 6mpbiri 250 . . . . . 6 (𝑥 = (𝐵 ∩ 𝒫 𝐴) → 𝑥𝐵)
87biantrurd 530 . . . . 5 (𝑥 = (𝐵 ∩ 𝒫 𝐴) → (𝐴 = 𝑥 ↔ (𝑥𝐵𝐴 = 𝑥)))
9 unieq 4666 . . . . . 6 (𝑥 = (𝐵 ∩ 𝒫 𝐴) → 𝑥 = (𝐵 ∩ 𝒫 𝐴))
109eqeq2d 2835 . . . . 5 (𝑥 = (𝐵 ∩ 𝒫 𝐴) → (𝐴 = 𝑥𝐴 = (𝐵 ∩ 𝒫 𝐴)))
118, 10bitr3d 273 . . . 4 (𝑥 = (𝐵 ∩ 𝒫 𝐴) → ((𝑥𝐵𝐴 = 𝑥) ↔ 𝐴 = (𝐵 ∩ 𝒫 𝐴)))
1211spcegv 3511 . . 3 ((𝐵 ∩ 𝒫 𝐴) ∈ V → (𝐴 = (𝐵 ∩ 𝒫 𝐴) → ∃𝑥(𝑥𝐵𝐴 = 𝑥)))
133, 4, 12sylc 65 . 2 (𝐴 ∈ (topGen‘𝐵) → ∃𝑥(𝑥𝐵𝐴 = 𝑥))
14 eltg3i 21136 . . . . 5 ((𝐵𝑉𝑥𝐵) → 𝑥 ∈ (topGen‘𝐵))
15 eleq1 2894 . . . . 5 (𝐴 = 𝑥 → (𝐴 ∈ (topGen‘𝐵) ↔ 𝑥 ∈ (topGen‘𝐵)))
1614, 15syl5ibrcom 239 . . . 4 ((𝐵𝑉𝑥𝐵) → (𝐴 = 𝑥𝐴 ∈ (topGen‘𝐵)))
1716expimpd 447 . . 3 (𝐵𝑉 → ((𝑥𝐵𝐴 = 𝑥) → 𝐴 ∈ (topGen‘𝐵)))
1817exlimdv 2034 . 2 (𝐵𝑉 → (∃𝑥(𝑥𝐵𝐴 = 𝑥) → 𝐴 ∈ (topGen‘𝐵)))
1913, 18impbid2 218 1 (𝐵𝑉 → (𝐴 ∈ (topGen‘𝐵) ↔ ∃𝑥(𝑥𝐵𝐴 = 𝑥)))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 198  wa 386   = wceq 1658  wex 1880  wcel 2166  Vcvv 3414  cin 3797  wss 3798  𝒫 cpw 4378   cuni 4658  dom cdm 5342  cfv 6123  topGenctg 16451
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1896  ax-4 1910  ax-5 2011  ax-6 2077  ax-7 2114  ax-8 2168  ax-9 2175  ax-10 2194  ax-11 2209  ax-12 2222  ax-13 2391  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 881  df-3an 1115  df-tru 1662  df-ex 1881  df-nf 1885  df-sb 2070  df-mo 2605  df-eu 2640  df-clab 2812  df-cleq 2818  df-clel 2821  df-nfc 2958  df-ral 3122  df-rex 3123  df-rab 3126  df-v 3416  df-sbc 3663  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-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-iota 6086  df-fun 6125  df-fv 6131  df-topgen 16457
This theorem is referenced by:  tgval3  21138  tgtop  21148  eltop3  21151  tgidm  21155  bastop1  21168  tgrest  21334  tgcn  21427  txbasval  21780  opnmblALT  23769  mbfimaopnlem  23821  isfne3  32876  fneuni  32880  dissneqlem  33733  tgqioo2  40569
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