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Theorem kqreg 21364
Description: The Kolmogorov quotient of a regular space is regular. By regr1 21363 it is also Hausdorff, so we can also say that a space is regular iff the Kolmogorov quotient is regular Hausdorff (T3). (Contributed by Mario Carneiro, 25-Aug-2015.)
Assertion
Ref Expression
kqreg (𝐽 ∈ Reg ↔ (KQ‘𝐽) ∈ Reg)

Proof of Theorem kqreg
Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 regtop 20947 . . . 4 (𝐽 ∈ Reg → 𝐽 ∈ Top)
2 eqid 2610 . . . . 5 𝐽 = 𝐽
32toptopon 20548 . . . 4 (𝐽 ∈ Top ↔ 𝐽 ∈ (TopOn‘ 𝐽))
41, 3sylib 207 . . 3 (𝐽 ∈ Reg → 𝐽 ∈ (TopOn‘ 𝐽))
5 eqid 2610 . . . 4 (𝑥 𝐽 ↦ {𝑦𝐽𝑥𝑦}) = (𝑥 𝐽 ↦ {𝑦𝐽𝑥𝑦})
65kqreglem1 21354 . . 3 ((𝐽 ∈ (TopOn‘ 𝐽) ∧ 𝐽 ∈ Reg) → (KQ‘𝐽) ∈ Reg)
74, 6mpancom 700 . 2 (𝐽 ∈ Reg → (KQ‘𝐽) ∈ Reg)
8 regtop 20947 . . . . 5 ((KQ‘𝐽) ∈ Reg → (KQ‘𝐽) ∈ Top)
9 kqtop 21358 . . . . 5 (𝐽 ∈ Top ↔ (KQ‘𝐽) ∈ Top)
108, 9sylibr 223 . . . 4 ((KQ‘𝐽) ∈ Reg → 𝐽 ∈ Top)
1110, 3sylib 207 . . 3 ((KQ‘𝐽) ∈ Reg → 𝐽 ∈ (TopOn‘ 𝐽))
125kqreglem2 21355 . . 3 ((𝐽 ∈ (TopOn‘ 𝐽) ∧ (KQ‘𝐽) ∈ Reg) → 𝐽 ∈ Reg)
1311, 12mpancom 700 . 2 ((KQ‘𝐽) ∈ Reg → 𝐽 ∈ Reg)
147, 13impbii 198 1 (𝐽 ∈ Reg ↔ (KQ‘𝐽) ∈ Reg)
Colors of variables: wff setvar class
Syntax hints:  wb 195  wcel 1977  {crab 2900   cuni 4372  cmpt 4643  cfv 5804  Topctop 20517  TopOnctopon 20518  Regcreg 20923  KQckq 21306
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-rep 4699  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-reu 2903  df-rab 2905  df-v 3175  df-sbc 3403  df-csb 3500  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-int 4411  df-iun 4457  df-iin 4458  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-rn 5049  df-res 5050  df-ima 5051  df-iota 5768  df-fun 5806  df-fn 5807  df-f 5808  df-f1 5809  df-fo 5810  df-f1o 5811  df-fv 5812  df-ov 6552  df-oprab 6553  df-mpt2 6554  df-map 7746  df-qtop 15990  df-top 20521  df-topon 20523  df-cld 20633  df-cls 20635  df-cn 20841  df-reg 20930  df-kq 21307
This theorem is referenced by: (None)
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