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Theorem indistps2 20626
 Description: The indiscrete topology on a set 𝐴 expressed as a topological space, using direct component assignments. Compare with indistps 20625. The advantage of this version is that it is the shortest to state and easiest to work with in most situations. Theorems indistpsALT 20627 and indistps2ALT 20628 show that the two forms can be derived from each other. (Contributed by NM, 24-Oct-2012.)
Hypotheses
Ref Expression
indistps2.a (Base‘𝐾) = 𝐴
indistps2.j (TopOpen‘𝐾) = {∅, 𝐴}
Assertion
Ref Expression
indistps2 𝐾 ∈ TopSp

Proof of Theorem indistps2
StepHypRef Expression
1 indistps2.a . 2 (Base‘𝐾) = 𝐴
2 indistps2.j . 2 (TopOpen‘𝐾) = {∅, 𝐴}
3 0ex 4718 . . . 4 ∅ ∈ V
4 fvex 6113 . . . . 5 (Base‘𝐾) ∈ V
51, 4eqeltrri 2685 . . . 4 𝐴 ∈ V
63, 5unipr 4385 . . 3 {∅, 𝐴} = (∅ ∪ 𝐴)
7 uncom 3719 . . 3 (∅ ∪ 𝐴) = (𝐴 ∪ ∅)
8 un0 3919 . . 3 (𝐴 ∪ ∅) = 𝐴
96, 7, 83eqtrri 2637 . 2 𝐴 = {∅, 𝐴}
10 indistop 20616 . 2 {∅, 𝐴} ∈ Top
111, 2, 9, 10istpsi 20559 1 𝐾 ∈ TopSp
 Colors of variables: wff setvar class Syntax hints:   = wceq 1475   ∈ wcel 1977  Vcvv 3173   ∪ cun 3538  ∅c0 3874  {cpr 4127  ∪ cuni 4372  ‘cfv 5804  Basecbs 15695  TopOpenctopn 15905  TopSpctps 20519 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-8 1979  ax-9 1986  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590  ax-sep 4709  ax-nul 4717  ax-pow 4769  ax-pr 4833  ax-un 6847 This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-3an 1033  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-eu 2462  df-mo 2463  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-ne 2782  df-ral 2901  df-rex 2902  df-rab 2905  df-v 3175  df-sbc 3403  df-dif 3543  df-un 3545  df-in 3547  df-ss 3554  df-nul 3875  df-if 4037  df-pw 4110  df-sn 4126  df-pr 4128  df-op 4132  df-uni 4373  df-br 4584  df-opab 4644  df-mpt 4645  df-id 4953  df-xp 5044  df-rel 5045  df-cnv 5046  df-co 5047  df-dm 5048  df-iota 5768  df-fun 5806  df-fv 5812  df-top 20521  df-topon 20523  df-topsp 20524 This theorem is referenced by: (None)
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