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Theorem lagsubg 19157

Description: Lagrange's 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 483	. . . . . . 7 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → 𝑋 ∈ Fin)
2		pwfi 9209	. . . . . . 7 ⊢ (𝑋 ∈ Fin ↔ 𝒫 𝑋 ∈ Fin)
3	1, 2	sylib 217	. . . . . 6 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → 𝒫 𝑋 ∈ Fin)
4		lagsubg.1	. . . . . . . . 9 ⊢ 𝑋 = (Base‘𝐺)
5		eqid 2728	. . . . . . . . 9 ⊢ (𝐺 ~_QG 𝑌) = (𝐺 ~_QG 𝑌)
6	4, 5	eqger 19140	. . . . . . . 8 ⊢ (𝑌 ∈ (SubGrp‘𝐺) → (𝐺 ~_QG 𝑌) Er 𝑋)
7	6	adantr 479	. . . . . . 7 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (𝐺 ~_QG 𝑌) Er 𝑋)
8	7	qsss 8803	. . . . . 6 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (𝑋 / (𝐺 ~_QG 𝑌)) ⊆ 𝒫 𝑋)
9	3, 8	ssfid 9298	. . . . 5 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (𝑋 / (𝐺 ~_QG 𝑌)) ∈ Fin)
10		hashcl 14355	. . . . 5 ⊢ ((𝑋 / (𝐺 ~_QG 𝑌)) ∈ Fin → (♯‘(𝑋 / (𝐺 ~_QG 𝑌))) ∈ ℕ₀)
11	9, 10	syl 17	. . . 4 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘(𝑋 / (𝐺 ~_QG 𝑌))) ∈ ℕ₀)
12	11	nn0zd 12622	. . 3 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘(𝑋 / (𝐺 ~_QG 𝑌))) ∈ ℤ)
13		id 22	. . . . . 6 ⊢ (𝑋 ∈ Fin → 𝑋 ∈ Fin)
14	4	subgss 19089	. . . . . 6 ⊢ (𝑌 ∈ (SubGrp‘𝐺) → 𝑌 ⊆ 𝑋)
15		ssfi 9204	. . . . . 6 ⊢ ((𝑋 ∈ Fin ∧ 𝑌 ⊆ 𝑋) → 𝑌 ∈ Fin)
16	13, 14, 15	syl2anr 595	. . . . 5 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → 𝑌 ∈ Fin)
17		hashcl 14355	. . . . 5 ⊢ (𝑌 ∈ Fin → (♯‘𝑌) ∈ ℕ₀)
18	16, 17	syl 17	. . . 4 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘𝑌) ∈ ℕ₀)
19	18	nn0zd 12622	. . 3 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘𝑌) ∈ ℤ)
20		dvdsmul2 16263	. . 3 ⊢ (((♯‘(𝑋 / (𝐺 ~_QG 𝑌))) ∈ ℤ ∧ (♯‘𝑌) ∈ ℤ) → (♯‘𝑌) ∥ ((♯‘(𝑋 / (𝐺 ~_QG 𝑌))) · (♯‘𝑌)))
21	12, 19, 20	syl2anc 582	. 2 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘𝑌) ∥ ((♯‘(𝑋 / (𝐺 ~_QG 𝑌))) · (♯‘𝑌)))
22		simpl 481	. . 3 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → 𝑌 ∈ (SubGrp‘𝐺))
23	4, 5, 22, 1	lagsubg2 19156	. 2 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘𝑋) = ((♯‘(𝑋 / (𝐺 ~_QG 𝑌))) · (♯‘𝑌)))
24	21, 23	breqtrrd 5180	1 ⊢ ((𝑌 ∈ (SubGrp‘𝐺) ∧ 𝑋 ∈ Fin) → (♯‘𝑌) ∥ (♯‘𝑋))

Colors of variables: wff setvar class

Syntax hints: → wi 4 ∧ wa 394 = wceq 1533 ∈ wcel 2098 ⊆ wss 3949 𝒫 cpw 4606 class class class wbr 5152 ‘cfv 6553 (class class class)co 7426 Er wer 8728 / cqs 8730 Fincfn 8970 · cmul 11151 ℕ₀cn0 12510 ℤcz 12596 ♯chash 14329 ∥ cdvds 16238 Basecbs 17187 SubGrpcsubg 19082 ~_QG cqg 19084

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1789 ax-4 1803 ax-5 1905 ax-6 1963 ax-7 2003 ax-8 2100 ax-9 2108 ax-10 2129 ax-11 2146 ax-12 2166 ax-ext 2699 ax-rep 5289 ax-sep 5303 ax-nul 5310 ax-pow 5369 ax-pr 5433 ax-un 7746 ax-inf2 9672 ax-cnex 11202 ax-resscn 11203 ax-1cn 11204 ax-icn 11205 ax-addcl 11206 ax-addrcl 11207 ax-mulcl 11208 ax-mulrcl 11209 ax-mulcom 11210 ax-addass 11211 ax-mulass 11212 ax-distr 11213 ax-i2m1 11214 ax-1ne0 11215 ax-1rid 11216 ax-rnegex 11217 ax-rrecex 11218 ax-cnre 11219 ax-pre-lttri 11220 ax-pre-lttrn 11221 ax-pre-ltadd 11222 ax-pre-mulgt0 11223 ax-pre-sup 11224

This theorem depends on definitions: df-bi 206 df-an 395 df-or 846 df-3or 1085 df-3an 1086 df-tru 1536 df-fal 1546 df-ex 1774 df-nf 1778 df-sb 2060 df-mo 2529 df-eu 2558 df-clab 2706 df-cleq 2720 df-clel 2806 df-nfc 2881 df-ne 2938 df-nel 3044 df-ral 3059 df-rex 3068 df-rmo 3374 df-reu 3375 df-rab 3431 df-v 3475 df-sbc 3779 df-csb 3895 df-dif 3952 df-un 3954 df-in 3956 df-ss 3966 df-pss 3968 df-nul 4327 df-if 4533 df-pw 4608 df-sn 4633 df-pr 4635 df-op 4639 df-uni 4913 df-int 4954 df-iun 5002 df-disj 5118 df-br 5153 df-opab 5215 df-mpt 5236 df-tr 5270 df-id 5580 df-eprel 5586 df-po 5594 df-so 5595 df-fr 5637 df-se 5638 df-we 5639 df-xp 5688 df-rel 5689 df-cnv 5690 df-co 5691 df-dm 5692 df-rn 5693 df-res 5694 df-ima 5695 df-pred 6310 df-ord 6377 df-on 6378 df-lim 6379 df-suc 6380 df-iota 6505 df-fun 6555 df-fn 6556 df-f 6557 df-f1 6558 df-fo 6559 df-f1o 6560 df-fv 6561 df-isom 6562 df-riota 7382 df-ov 7429 df-oprab 7430 df-mpo 7431 df-om 7877 df-1st 7999 df-2nd 8000 df-frecs 8293 df-wrecs 8324 df-recs 8398 df-rdg 8437 df-1o 8493 df-er 8731 df-ec 8733 df-qs 8737 df-en 8971 df-dom 8972 df-sdom 8973 df-fin 8974 df-sup 9473 df-oi 9541 df-card 9970 df-pnf 11288 df-mnf 11289 df-xr 11290 df-ltxr 11291 df-le 11292 df-sub 11484 df-neg 11485 df-div 11910 df-nn 12251 df-2 12313 df-3 12314 df-n0 12511 df-z 12597 df-uz 12861 df-rp 13015 df-fz 13525 df-fzo 13668 df-seq 14007 df-exp 14067 df-hash 14330 df-cj 15086 df-re 15087 df-im 15088 df-sqrt 15222 df-abs 15223 df-clim 15472 df-sum 15673 df-dvds 16239 df-sets 17140 df-slot 17158 df-ndx 17170 df-base 17188 df-ress 17217 df-plusg 17253 df-0g 17430 df-mgm 18607 df-sgrp 18686 df-mnd 18702 df-grp 18900 df-minusg 18901 df-subg 19085 df-eqg 19087

This theorem is referenced by: oddvds2 19528 fislw 19587 sylow3lem4 19592 ablfacrp2 20031 ablfac1c 20035 ablfac1eu 20037 prmgrpsimpgd 20078

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