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Theorem lagsubg 17857

Description: Lagrange theorem for Groups: the order of any subgroup of a finite group is a divisor of the order of the group. This is Metamath 100 proof #71. (Contributed by Mario Carneiro, 11-Jul-2014.) (Revised by Mario Carneiro, 12-Aug-2015.)

**Hypothesis**
Ref	Expression
lagsubg.1	⊢ 𝑋 = (Base‘𝐺)

**Assertion**
Ref	Expression
lagsubg	⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘𝑌) ∥ (♯‘𝑋))

**Proof of Theorem lagsubg**
Step	Hyp	Ref	Expression
1		simpr 471	. . . . . . 7 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → 𝑋 ∈ Fin)
2		pwfi 8415	. . . . . . 7 ⊢ (𝑋 ∈ Fin ↔ 𝒫 𝑋 ∈ Fin)
3	1, 2	sylib 208	. . . . . 6 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → 𝒫 𝑋 ∈ Fin)
4		lagsubg.1	. . . . . . . . 9 ⊢ 𝑋 = (Base‘𝐺)
5		eqid 2771	. . . . . . . . 9 ⊢ (𝐺 ~_QG 𝑌) = (𝐺 ~_QG 𝑌)
6	4, 5	eqger 17845	. . . . . . . 8 ⊢ (𝑌 ∈ (SubGrp‘𝐺) → (𝐺 ~_QG 𝑌) Er 𝑋)
7	6	adantr 466	. . . . . . 7 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (𝐺 ~_QG 𝑌) Er 𝑋)
8	7	qsss 7958	. . . . . 6 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (𝑋 / (𝐺 ~_QG 𝑌)) ⊆ 𝒫 𝑋)
9		ssfi 8334	. . . . . 6 ⊢ ((𝒫 𝑋 ∈ Fin ∧ (𝑋 / (𝐺 ~_QG 𝑌)) ⊆ 𝒫 𝑋) → (𝑋 / (𝐺 ~_QG 𝑌)) ∈ Fin)
10	3, 8, 9	syl2anc 573	. . . . 5 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (𝑋 / (𝐺 ~_QG 𝑌)) ∈ Fin)
11		hashcl 13342	. . . . 5 ⊢ ((𝑋 / (𝐺 ~_QG 𝑌)) ∈ Fin → (♯‘(𝑋 / (𝐺 ~_QG 𝑌))) ∈ ℕ₀)
12	10, 11	syl 17	. . . 4 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘(𝑋 / (𝐺 ~_QG 𝑌))) ∈ ℕ₀)
13	12	nn0zd 11680	. . 3 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘(𝑋 / (𝐺 ~_QG 𝑌))) ∈ ℤ)
14		id 22	. . . . . 6 ⊢ (𝑋 ∈ Fin → 𝑋 ∈ Fin)
15	4	subgss 17796	. . . . . 6 ⊢ (𝑌 ∈ (SubGrp‘𝐺) → 𝑌 ⊆ 𝑋)
16		ssfi 8334	. . . . . 6 ⊢ ((𝑋 ∈ Fin ∧ 𝑌 ⊆ 𝑋) → 𝑌 ∈ Fin)
17	14, 15, 16	syl2anr 584	. . . . 5 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → 𝑌 ∈ Fin)
18		hashcl 13342	. . . . 5 ⊢ (𝑌 ∈ Fin → (♯‘𝑌) ∈ ℕ₀)
19	17, 18	syl 17	. . . 4 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘𝑌) ∈ ℕ₀)
20	19	nn0zd 11680	. . 3 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘𝑌) ∈ ℤ)
21		dvdsmul2 15206	. . 3 ⊢ (((♯‘(𝑋 / (𝐺 ~_QG 𝑌))) ∈ ℤ ∧ (♯‘𝑌) ∈ ℤ) → (♯‘𝑌) ∥ ((♯‘(𝑋 / (𝐺 ~_QG 𝑌))) · (♯‘𝑌)))
22	13, 20, 21	syl2anc 573	. 2 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘𝑌) ∥ ((♯‘(𝑋 / (𝐺 ~_QG 𝑌))) · (♯‘𝑌)))
23		simpl 468	. . 3 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → 𝑌 ∈ (SubGrp‘𝐺))
24	4, 5, 23, 1	lagsubg2 17856	. 2 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘𝑋) = ((♯‘(𝑋 / (𝐺 ~_QG 𝑌))) · (♯‘𝑌)))
25	22, 24	breqtrrd 4814	1 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘𝑌) ∥ (♯‘𝑋))

Colors of variables: wff setvar class

Syntax hints: → wi 4 ∧ wa 382 = wceq 1631 ∈ wcel 2145 ⊆ wss 3723 𝒫 cpw 4297 class class class wbr 4786 ‘cfv 6029 (class class class)co 6791 Er wer 7891 / cqs 7893 Fincfn 8107 · cmul 10141 ℕ₀cn0 11492 ℤcz 11577 ♯chash 13314 ∥ cdvds 15182 Basecbs 16057 SubGrpcsubg 17789 ~_QG cqg 17791

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1870 ax-4 1885 ax-5 1991 ax-6 2057 ax-7 2093 ax-8 2147 ax-9 2154 ax-10 2174 ax-11 2190 ax-12 2203 ax-13 2408 ax-ext 2751 ax-rep 4904 ax-sep 4915 ax-nul 4923 ax-pow 4974 ax-pr 5034 ax-un 7094 ax-inf2 8700 ax-cnex 10192 ax-resscn 10193 ax-1cn 10194 ax-icn 10195 ax-addcl 10196 ax-addrcl 10197 ax-mulcl 10198 ax-mulrcl 10199 ax-mulcom 10200 ax-addass 10201 ax-mulass 10202 ax-distr 10203 ax-i2m1 10204 ax-1ne0 10205 ax-1rid 10206 ax-rnegex 10207 ax-rrecex 10208 ax-cnre 10209 ax-pre-lttri 10210 ax-pre-lttrn 10211 ax-pre-ltadd 10212 ax-pre-mulgt0 10213 ax-pre-sup 10214

This theorem depends on definitions: df-bi 197 df-an 383 df-or 837 df-3or 1072 df-3an 1073 df-tru 1634 df-fal 1637 df-ex 1853 df-nf 1858 df-sb 2050 df-eu 2622 df-mo 2623 df-clab 2758 df-cleq 2764 df-clel 2767 df-nfc 2902 df-ne 2944 df-nel 3047 df-ral 3066 df-rex 3067 df-reu 3068 df-rmo 3069 df-rab 3070 df-v 3353 df-sbc 3588 df-csb 3683 df-dif 3726 df-un 3728 df-in 3730 df-ss 3737 df-pss 3739 df-nul 4064 df-if 4226 df-pw 4299 df-sn 4317 df-pr 4319 df-tp 4321 df-op 4323 df-uni 4575 df-int 4612 df-iun 4656 df-disj 4755 df-br 4787 df-opab 4847 df-mpt 4864 df-tr 4887 df-id 5157 df-eprel 5162 df-po 5170 df-so 5171 df-fr 5208 df-se 5209 df-we 5210 df-xp 5255 df-rel 5256 df-cnv 5257 df-co 5258 df-dm 5259 df-rn 5260 df-res 5261 df-ima 5262 df-pred 5821 df-ord 5867 df-on 5868 df-lim 5869 df-suc 5870 df-iota 5992 df-fun 6031 df-fn 6032 df-f 6033 df-f1 6034 df-fo 6035 df-f1o 6036 df-fv 6037 df-isom 6038 df-riota 6752 df-ov 6794 df-oprab 6795 df-mpt2 6796 df-om 7211 df-1st 7313 df-2nd 7314 df-wrecs 7557 df-recs 7619 df-rdg 7657 df-1o 7711 df-2o 7712 df-oadd 7715 df-er 7894 df-ec 7896 df-qs 7900 df-map 8009 df-en 8108 df-dom 8109 df-sdom 8110 df-fin 8111 df-sup 8502 df-oi 8569 df-card 8963 df-pnf 10276 df-mnf 10277 df-xr 10278 df-ltxr 10279 df-le 10280 df-sub 10468 df-neg 10469 df-div 10885 df-nn 11221 df-2 11279 df-3 11280 df-n0 11493 df-z 11578 df-uz 11887 df-rp 12029 df-fz 12527 df-fzo 12667 df-seq 13002 df-exp 13061 df-hash 13315 df-cj 14040 df-re 14041 df-im 14042 df-sqrt 14176 df-abs 14177 df-clim 14420 df-sum 14618 df-dvds 15183 df-ndx 16060 df-slot 16061 df-base 16063 df-sets 16064 df-ress 16065 df-plusg 16155 df-0g 16303 df-mgm 17443 df-sgrp 17485 df-mnd 17496 df-grp 17626 df-minusg 17627 df-subg 17792 df-eqg 17794

This theorem is referenced by: oddvds2 18183 fislw 18240 sylow3lem4 18245 ablfacrp2 18667 ablfac1c 18671 ablfac1eu 18673

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