Theorem indistgp 23251

Description: Any group equipped with the indiscrete topology is a topological group. (Contributed by Mario Carneiro, 14-Aug-2015.)

Hypotheses

Ref	Expression
distgp.1	⊢ 𝐵 = (Base‘𝐺)
distgp.2	⊢ 𝐽 = (TopOpen‘𝐺)

Assertion

Ref	Expression
indistgp	⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → 𝐺 ∈ TopGrp)

Proof of Theorem indistgp

Step	Hyp	Ref	Expression
1		simpl 483	. 2 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → 𝐺 ∈ Grp)
2		simpr 485	. . . 4 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → 𝐽 = {∅, 𝐵})
3		distgp.1	. . . . . 6 ⊢ 𝐵 = (Base‘𝐺)
4	3	fvexi 6788	. . . . 5 ⊢ 𝐵 ∈ V
5		indistopon 22151	. . . . 5 ⊢ (𝐵 ∈ V → {∅, 𝐵} ∈ (TopOn‘𝐵))
6	4, 5	ax-mp 5	. . . 4 ⊢ {∅, 𝐵} ∈ (TopOn‘𝐵)
7	2, 6	eqeltrdi 2847	. . 3 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → 𝐽 ∈ (TopOn‘𝐵))
8		distgp.2	. . . 4 ⊢ 𝐽 = (TopOpen‘𝐺)
9	3, 8	istps 22083	. . 3 ⊢ (𝐺 ∈ TopSp ↔ 𝐽 ∈ (TopOn‘𝐵))
10	7, 9	sylibr 233	. 2 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → 𝐺 ∈ TopSp)
11		eqid 2738	. . . . . 6 ⊢ (-g‘𝐺) = (-g‘𝐺)
12	3, 11	grpsubf 18654	. . . . 5 ⊢ (𝐺 ∈ Grp → (-g‘𝐺):(𝐵 × 𝐵)⟶𝐵)
13	12	adantr 481	. . . 4 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → (-g‘𝐺):(𝐵 × 𝐵)⟶𝐵)
14	4, 4	xpex 7603	. . . . 5 ⊢ (𝐵 × 𝐵) ∈ V
15	4, 14	elmap 8659	. . . 4 ⊢ ((-g‘𝐺) ∈ (𝐵 ↑m (𝐵 × 𝐵)) ↔ (-g‘𝐺):(𝐵 × 𝐵)⟶𝐵)
16	13, 15	sylibr 233	. . 3 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → (-g‘𝐺) ∈ (𝐵 ↑m (𝐵 × 𝐵)))
17	2	oveq2d 7291	. . . 4 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → ((𝐽 ×t 𝐽) Cn 𝐽) = ((𝐽 ×t 𝐽) Cn {∅, 𝐵}))
18		txtopon 22742	. . . . . 6 ⊢ ((𝐽 ∈ (TopOn‘𝐵) ∧ 𝐽 ∈ (TopOn‘𝐵)) → (𝐽 ×t 𝐽) ∈ (TopOn‘(𝐵 × 𝐵)))
19	7, 7, 18	syl2anc 584	. . . . 5 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → (𝐽 ×t 𝐽) ∈ (TopOn‘(𝐵 × 𝐵)))
20		cnindis 22443	. . . . 5 ⊢ (((𝐽 ×t 𝐽) ∈ (TopOn‘(𝐵 × 𝐵)) ∧ 𝐵 ∈ V) → ((𝐽 ×t 𝐽) Cn {∅, 𝐵}) = (𝐵 ↑m (𝐵 × 𝐵)))
21	19, 4, 20	sylancl 586	. . . 4 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → ((𝐽 ×t 𝐽) Cn {∅, 𝐵}) = (𝐵 ↑m (𝐵 × 𝐵)))
22	17, 21	eqtrd 2778	. . 3 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → ((𝐽 ×t 𝐽) Cn 𝐽) = (𝐵 ↑m (𝐵 × 𝐵)))
23	16, 22	eleqtrrd 2842	. 2 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → (-g‘𝐺) ∈ ((𝐽 ×t 𝐽) Cn 𝐽))
24	8, 11	istgp2 23242	. 2 ⊢ (𝐺 ∈ TopGrp ↔ (𝐺 ∈ Grp ∧ 𝐺 ∈ TopSp ∧ (-g‘𝐺) ∈ ((𝐽 ×t 𝐽) Cn 𝐽)))
25	1, 10, 23, 24	syl3anbrc 1342	1 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → 𝐺 ∈ TopGrp)

Syntax hints:   → wi 4   ∧ wa 396   = wceq 1539   ∈ wcel 2106  Vcvv 3432  ∅c0 4256  {cpr 4563   × cxp 5587  ⟶wf 6429  ‘cfv 6433  (class class class)co 7275   ↑_m cmap 8615  Basecbs 16912  TopOpenctopn 17132  Grpcgrp 18577  -_gcsg 18579  TopOnctopon 22059  TopSpctps 22081   Cn ccn 22375   ×_t ctx 22711  TopGrpctgp 23222

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1798  ax-4 1812  ax-5 1913  ax-6 1971  ax-7 2011  ax-8 2108  ax-9 2116  ax-10 2137  ax-11 2154  ax-12 2171  ax-ext 2709  ax-sep 5223  ax-nul 5230  ax-pow 5288  ax-pr 5352  ax-un 7588

This theorem depends on definitions:  df-bi 206  df-an 397  df-or 845  df-3an 1088  df-tru 1542  df-fal 1552  df-ex 1783  df-nf 1787  df-sb 2068  df-mo 2540  df-eu 2569  df-clab 2716  df-cleq 2730  df-clel 2816  df-nfc 2889  df-ne 2944  df-ral 3069  df-rex 3070  df-rmo 3071  df-reu 3072  df-rab 3073  df-v 3434  df-sbc 3717  df-csb 3833  df-dif 3890  df-un 3892  df-in 3894  df-ss 3904  df-nul 4257  df-if 4460  df-pw 4535  df-sn 4562  df-pr 4564  df-op 4568  df-uni 4840  df-iun 4926  df-br 5075  df-opab 5137  df-mpt 5158  df-id 5489  df-xp 5595  df-rel 5596  df-cnv 5597  df-co 5598  df-dm 5599  df-rn 5600  df-res 5601  df-ima 5602  df-iota 6391  df-fun 6435  df-fn 6436  df-f 6437  df-f1 6438  df-fo 6439  df-f1o 6440  df-fv 6441  df-riota 7232  df-ov 7278  df-oprab 7279  df-mpo 7280  df-1st 7831  df-2nd 7832  df-map 8617  df-0g 17152  df-topgen 17154  df-plusf 18325  df-mgm 18326  df-sgrp 18375  df-mnd 18386  df-grp 18580  df-minusg 18581  df-sbg 18582  df-top 22043  df-topon 22060  df-topsp 22082  df-bases 22096  df-cn 22378  df-cnp 22379  df-tx 22713  df-tmd 23223  df-tgp 23224

This theorem is referenced by: (None)