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Theorem tgtop 20979
 Description: A topology is its own basis. (Contributed by NM, 18-Jul-2006.)
Assertion
Ref Expression
tgtop (𝐽 ∈ Top → (topGen‘𝐽) = 𝐽)

Proof of Theorem tgtop
Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 eltg3 20968 . . . 4 (𝐽 ∈ Top → (𝑥 ∈ (topGen‘𝐽) ↔ ∃𝑦(𝑦𝐽𝑥 = 𝑦)))
2 simpr 479 . . . . . . 7 (((𝐽 ∈ Top ∧ 𝑦𝐽) ∧ 𝑥 = 𝑦) → 𝑥 = 𝑦)
3 uniopn 20904 . . . . . . . 8 ((𝐽 ∈ Top ∧ 𝑦𝐽) → 𝑦𝐽)
43adantr 472 . . . . . . 7 (((𝐽 ∈ Top ∧ 𝑦𝐽) ∧ 𝑥 = 𝑦) → 𝑦𝐽)
52, 4eqeltrd 2839 . . . . . 6 (((𝐽 ∈ Top ∧ 𝑦𝐽) ∧ 𝑥 = 𝑦) → 𝑥𝐽)
65expl 649 . . . . 5 (𝐽 ∈ Top → ((𝑦𝐽𝑥 = 𝑦) → 𝑥𝐽))
76exlimdv 2010 . . . 4 (𝐽 ∈ Top → (∃𝑦(𝑦𝐽𝑥 = 𝑦) → 𝑥𝐽))
81, 7sylbid 230 . . 3 (𝐽 ∈ Top → (𝑥 ∈ (topGen‘𝐽) → 𝑥𝐽))
98ssrdv 3750 . 2 (𝐽 ∈ Top → (topGen‘𝐽) ⊆ 𝐽)
10 bastg 20972 . 2 (𝐽 ∈ Top → 𝐽 ⊆ (topGen‘𝐽))
119, 10eqssd 3761 1 (𝐽 ∈ Top → (topGen‘𝐽) = 𝐽)
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ∧ wa 383   = wceq 1632  ∃wex 1853   ∈ wcel 2139   ⊆ wss 3715  ∪ cuni 4588  ‘cfv 6049  topGenctg 16300  Topctop 20900 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1871  ax-4 1886  ax-5 1988  ax-6 2054  ax-7 2090  ax-8 2141  ax-9 2148  ax-10 2168  ax-11 2183  ax-12 2196  ax-13 2391  ax-ext 2740  ax-sep 4933  ax-nul 4941  ax-pow 4992  ax-pr 5055  ax-un 7114 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-3an 1074  df-tru 1635  df-ex 1854  df-nf 1859  df-sb 2047  df-eu 2611  df-mo 2612  df-clab 2747  df-cleq 2753  df-clel 2756  df-nfc 2891  df-ne 2933  df-ral 3055  df-rex 3056  df-rab 3059  df-v 3342  df-sbc 3577  df-dif 3718  df-un 3720  df-in 3722  df-ss 3729  df-nul 4059  df-if 4231  df-pw 4304  df-sn 4322  df-pr 4324  df-op 4328  df-uni 4589  df-br 4805  df-opab 4865  df-mpt 4882  df-id 5174  df-xp 5272  df-rel 5273  df-cnv 5274  df-co 5275  df-dm 5276  df-iota 6012  df-fun 6051  df-fv 6057  df-topgen 16306  df-top 20901 This theorem is referenced by:  eltop  20980  eltop2  20981  eltop3  20982  bastop  20987  tgtop11  20988  basgen  20994  tgfiss  20997  bastop1  20999  resttop  21166  dis1stc  21504  alexsubALTlem1  22052  xrtgioo  22810  topfne  32655  topfneec  32656  topfneec2  32657  dissneqlem  33498
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