Theorem indistgp 22705

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 486	. 2 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → 𝐺 ∈ Grp)
2		simpr 488	. . . 4 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → 𝐽 = {∅, 𝐵})
3		distgp.1	. . . . . 6 ⊢ 𝐵 = (Base‘𝐺)
4	3	fvexi 6659	. . . . 5 ⊢ 𝐵 ∈ V
5		indistopon 21606	. . . . 5 ⊢ (𝐵 ∈ V → {∅, 𝐵} ∈ (TopOn‘𝐵))
6	4, 5	ax-mp 5	. . . 4 ⊢ {∅, 𝐵} ∈ (TopOn‘𝐵)
7	2, 6	eqeltrdi 2898	. . 3 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → 𝐽 ∈ (TopOn‘𝐵))
8		distgp.2	. . . 4 ⊢ 𝐽 = (TopOpen‘𝐺)
9	3, 8	istps 21539	. . 3 ⊢ (𝐺 ∈ TopSp ↔ 𝐽 ∈ (TopOn‘𝐵))
10	7, 9	sylibr 237	. 2 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → 𝐺 ∈ TopSp)
11		eqid 2798	. . . . . 6 ⊢ (-g‘𝐺) = (-g‘𝐺)
12	3, 11	grpsubf 18170	. . . . 5 ⊢ (𝐺 ∈ Grp → (-g‘𝐺):(𝐵 × 𝐵)⟶𝐵)
13	12	adantr 484	. . . 4 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → (-g‘𝐺):(𝐵 × 𝐵)⟶𝐵)
14	4, 4	xpex 7456	. . . . 5 ⊢ (𝐵 × 𝐵) ∈ V
15	4, 14	elmap 8418	. . . 4 ⊢ ((-g‘𝐺) ∈ (𝐵 ↑m (𝐵 × 𝐵)) ↔ (-g‘𝐺):(𝐵 × 𝐵)⟶𝐵)
16	13, 15	sylibr 237	. . 3 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → (-g‘𝐺) ∈ (𝐵 ↑m (𝐵 × 𝐵)))
17	2	oveq2d 7151	. . . 4 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → ((𝐽 ×t 𝐽) Cn 𝐽) = ((𝐽 ×t 𝐽) Cn {∅, 𝐵}))
18		txtopon 22196	. . . . . 6 ⊢ ((𝐽 ∈ (TopOn‘𝐵) ∧ 𝐽 ∈ (TopOn‘𝐵)) → (𝐽 ×t 𝐽) ∈ (TopOn‘(𝐵 × 𝐵)))
19	7, 7, 18	syl2anc 587	. . . . 5 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → (𝐽 ×t 𝐽) ∈ (TopOn‘(𝐵 × 𝐵)))
20		cnindis 21897	. . . . 5 ⊢ (((𝐽 ×t 𝐽) ∈ (TopOn‘(𝐵 × 𝐵)) ∧ 𝐵 ∈ V) → ((𝐽 ×t 𝐽) Cn {∅, 𝐵}) = (𝐵 ↑m (𝐵 × 𝐵)))
21	19, 4, 20	sylancl 589	. . . 4 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → ((𝐽 ×t 𝐽) Cn {∅, 𝐵}) = (𝐵 ↑m (𝐵 × 𝐵)))
22	17, 21	eqtrd 2833	. . 3 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → ((𝐽 ×t 𝐽) Cn 𝐽) = (𝐵 ↑m (𝐵 × 𝐵)))
23	16, 22	eleqtrrd 2893	. 2 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → (-g‘𝐺) ∈ ((𝐽 ×t 𝐽) Cn 𝐽))
24	8, 11	istgp2 22696	. 2 ⊢ (𝐺 ∈ TopGrp ↔ (𝐺 ∈ Grp ∧ 𝐺 ∈ TopSp ∧ (-g‘𝐺) ∈ ((𝐽 ×t 𝐽) Cn 𝐽)))
25	1, 10, 23, 24	syl3anbrc 1340	1 ⊢ ((𝐺 ∈ Grp ∧ 𝐽 = {∅, 𝐵}) → 𝐺 ∈ TopGrp)

Syntax hints:   → wi 4   ∧ wa 399   = wceq 1538   ∈ wcel 2111  Vcvv 3441  ∅c0 4243  {cpr 4527   × cxp 5517  ⟶wf 6320  ‘cfv 6324  (class class class)co 7135   ↑_m cmap 8389  Basecbs 16475  TopOpenctopn 16687  Grpcgrp 18095  -_gcsg 18097  TopOnctopon 21515  TopSpctps 21537   Cn ccn 21829   ×_t ctx 22165  TopGrpctgp 22676

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1911  ax-6 1970  ax-7 2015  ax-8 2113  ax-9 2121  ax-10 2142  ax-11 2158  ax-12 2175  ax-ext 2770  ax-sep 5167  ax-nul 5174  ax-pow 5231  ax-pr 5295  ax-un 7441

This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-3an 1086  df-tru 1541  df-ex 1782  df-nf 1786  df-sb 2070  df-mo 2598  df-eu 2629  df-clab 2777  df-cleq 2791  df-clel 2870  df-nfc 2938  df-ne 2988  df-ral 3111  df-rex 3112  df-reu 3113  df-rmo 3114  df-rab 3115  df-v 3443  df-sbc 3721  df-csb 3829  df-dif 3884  df-un 3886  df-in 3888  df-ss 3898  df-nul 4244  df-if 4426  df-pw 4499  df-sn 4526  df-pr 4528  df-op 4532  df-uni 4801  df-iun 4883  df-br 5031  df-opab 5093  df-mpt 5111  df-id 5425  df-xp 5525  df-rel 5526  df-cnv 5527  df-co 5528  df-dm 5529  df-rn 5530  df-res 5531  df-ima 5532  df-iota 6283  df-fun 6326  df-fn 6327  df-f 6328  df-f1 6329  df-fo 6330  df-f1o 6331  df-fv 6332  df-riota 7093  df-ov 7138  df-oprab 7139  df-mpo 7140  df-1st 7671  df-2nd 7672  df-map 8391  df-0g 16707  df-topgen 16709  df-plusf 17843  df-mgm 17844  df-sgrp 17893  df-mnd 17904  df-grp 18098  df-minusg 18099  df-sbg 18100  df-top 21499  df-topon 21516  df-topsp 21538  df-bases 21551  df-cn 21832  df-cnp 21833  df-tx 22167  df-tmd 22677  df-tgp 22678

This theorem is referenced by: (None)