Theorem isnsg2 13726

Description: Weaken the condition of isnsg 13725 to only one side of the implication. (Contributed by Mario Carneiro, 18-Jan-2015.)

Hypotheses

Ref	Expression
isnsg.1	⊢ 𝑋 = (Base‘𝐺)
isnsg.2	⊢ + = (+g‘𝐺)

Assertion

Ref	Expression
isnsg2	⊢ (𝑆 ∈ (NrmSGrp‘𝐺) ↔ (𝑆 ∈ (SubGrp‘𝐺) ∧ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆)))

Distinct variable groups:   𝑥,𝑦,𝐺   𝑥, + ,𝑦   𝑥,𝑆,𝑦   𝑥,𝑋,𝑦

Proof of Theorem isnsg2

Dummy variable 𝑧 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		isnsg.1	. . 3 ⊢ 𝑋 = (Base‘𝐺)
2		isnsg.2	. . 3 ⊢ + = (+g‘𝐺)
3	1, 2	isnsg 13725	. 2 ⊢ (𝑆 ∈ (NrmSGrp‘𝐺) ↔ (𝑆 ∈ (SubGrp‘𝐺) ∧ ∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑥 + 𝑧) ∈ 𝑆 ↔ (𝑧 + 𝑥) ∈ 𝑆)))
4		dfbi2 388	. . . . . . 7 ⊢ (((𝑥 + 𝑧) ∈ 𝑆 ↔ (𝑧 + 𝑥) ∈ 𝑆) ↔ (((𝑥 + 𝑧) ∈ 𝑆 → (𝑧 + 𝑥) ∈ 𝑆) ∧ ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆)))
5	4	ralbii 2536	. . . . . 6 ⊢ (∀𝑧 ∈ 𝑋 ((𝑥 + 𝑧) ∈ 𝑆 ↔ (𝑧 + 𝑥) ∈ 𝑆) ↔ ∀𝑧 ∈ 𝑋 (((𝑥 + 𝑧) ∈ 𝑆 → (𝑧 + 𝑥) ∈ 𝑆) ∧ ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆)))
6	5	ralbii 2536	. . . . 5 ⊢ (∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑥 + 𝑧) ∈ 𝑆 ↔ (𝑧 + 𝑥) ∈ 𝑆) ↔ ∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 (((𝑥 + 𝑧) ∈ 𝑆 → (𝑧 + 𝑥) ∈ 𝑆) ∧ ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆)))
7		r19.26-2 2660	. . . . 5 ⊢ (∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 (((𝑥 + 𝑧) ∈ 𝑆 → (𝑧 + 𝑥) ∈ 𝑆) ∧ ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆)) ↔ (∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑥 + 𝑧) ∈ 𝑆 → (𝑧 + 𝑥) ∈ 𝑆) ∧ ∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆)))
8	6, 7	bitri 184	. . . 4 ⊢ (∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑥 + 𝑧) ∈ 𝑆 ↔ (𝑧 + 𝑥) ∈ 𝑆) ↔ (∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑥 + 𝑧) ∈ 𝑆 → (𝑧 + 𝑥) ∈ 𝑆) ∧ ∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆)))
9		oveq2 6002	. . . . . . . . 9 ⊢ (𝑧 = 𝑦 → (𝑥 + 𝑧) = (𝑥 + 𝑦))
10	9	eleq1d 2298	. . . . . . . 8 ⊢ (𝑧 = 𝑦 → ((𝑥 + 𝑧) ∈ 𝑆 ↔ (𝑥 + 𝑦) ∈ 𝑆))
11		oveq1 6001	. . . . . . . . 9 ⊢ (𝑧 = 𝑦 → (𝑧 + 𝑥) = (𝑦 + 𝑥))
12	11	eleq1d 2298	. . . . . . . 8 ⊢ (𝑧 = 𝑦 → ((𝑧 + 𝑥) ∈ 𝑆 ↔ (𝑦 + 𝑥) ∈ 𝑆))
13	10, 12	imbi12d 234	. . . . . . 7 ⊢ (𝑧 = 𝑦 → (((𝑥 + 𝑧) ∈ 𝑆 → (𝑧 + 𝑥) ∈ 𝑆) ↔ ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆)))
14	13	cbvralvw 2769	. . . . . 6 ⊢ (∀𝑧 ∈ 𝑋 ((𝑥 + 𝑧) ∈ 𝑆 → (𝑧 + 𝑥) ∈ 𝑆) ↔ ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆))
15	14	ralbii 2536	. . . . 5 ⊢ (∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑥 + 𝑧) ∈ 𝑆 → (𝑧 + 𝑥) ∈ 𝑆) ↔ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆))
16		ralcom 2694	. . . . . 6 ⊢ (∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆) ↔ ∀𝑧 ∈ 𝑋 ∀𝑥 ∈ 𝑋 ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆))
17		oveq2 6002	. . . . . . . . . 10 ⊢ (𝑥 = 𝑦 → (𝑧 + 𝑥) = (𝑧 + 𝑦))
18	17	eleq1d 2298	. . . . . . . . 9 ⊢ (𝑥 = 𝑦 → ((𝑧 + 𝑥) ∈ 𝑆 ↔ (𝑧 + 𝑦) ∈ 𝑆))
19		oveq1 6001	. . . . . . . . . 10 ⊢ (𝑥 = 𝑦 → (𝑥 + 𝑧) = (𝑦 + 𝑧))
20	19	eleq1d 2298	. . . . . . . . 9 ⊢ (𝑥 = 𝑦 → ((𝑥 + 𝑧) ∈ 𝑆 ↔ (𝑦 + 𝑧) ∈ 𝑆))
21	18, 20	imbi12d 234	. . . . . . . 8 ⊢ (𝑥 = 𝑦 → (((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆) ↔ ((𝑧 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑧) ∈ 𝑆)))
22	21	cbvralvw 2769	. . . . . . 7 ⊢ (∀𝑥 ∈ 𝑋 ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆) ↔ ∀𝑦 ∈ 𝑋 ((𝑧 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑧) ∈ 𝑆))
23	22	ralbii 2536	. . . . . 6 ⊢ (∀𝑧 ∈ 𝑋 ∀𝑥 ∈ 𝑋 ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆) ↔ ∀𝑧 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑧 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑧) ∈ 𝑆))
24		oveq1 6001	. . . . . . . . . 10 ⊢ (𝑧 = 𝑥 → (𝑧 + 𝑦) = (𝑥 + 𝑦))
25	24	eleq1d 2298	. . . . . . . . 9 ⊢ (𝑧 = 𝑥 → ((𝑧 + 𝑦) ∈ 𝑆 ↔ (𝑥 + 𝑦) ∈ 𝑆))
26		oveq2 6002	. . . . . . . . . 10 ⊢ (𝑧 = 𝑥 → (𝑦 + 𝑧) = (𝑦 + 𝑥))
27	26	eleq1d 2298	. . . . . . . . 9 ⊢ (𝑧 = 𝑥 → ((𝑦 + 𝑧) ∈ 𝑆 ↔ (𝑦 + 𝑥) ∈ 𝑆))
28	25, 27	imbi12d 234	. . . . . . . 8 ⊢ (𝑧 = 𝑥 → (((𝑧 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑧) ∈ 𝑆) ↔ ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆)))
29	28	ralbidv 2530	. . . . . . 7 ⊢ (𝑧 = 𝑥 → (∀𝑦 ∈ 𝑋 ((𝑧 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑧) ∈ 𝑆) ↔ ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆)))
30	29	cbvralvw 2769	. . . . . 6 ⊢ (∀𝑧 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑧 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑧) ∈ 𝑆) ↔ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆))
31	16, 23, 30	3bitri 206	. . . . 5 ⊢ (∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆) ↔ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆))
32	15, 31	anbi12i 460	. . . 4 ⊢ ((∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑥 + 𝑧) ∈ 𝑆 → (𝑧 + 𝑥) ∈ 𝑆) ∧ ∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑧 + 𝑥) ∈ 𝑆 → (𝑥 + 𝑧) ∈ 𝑆)) ↔ (∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆) ∧ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆)))
33		anidm 396	. . . 4 ⊢ ((∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆) ∧ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆)) ↔ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆))
34	8, 32, 33	3bitri 206	. . 3 ⊢ (∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑥 + 𝑧) ∈ 𝑆 ↔ (𝑧 + 𝑥) ∈ 𝑆) ↔ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆))
35	34	anbi2i 457	. 2 ⊢ ((𝑆 ∈ (SubGrp‘𝐺) ∧ ∀𝑥 ∈ 𝑋 ∀𝑧 ∈ 𝑋 ((𝑥 + 𝑧) ∈ 𝑆 ↔ (𝑧 + 𝑥) ∈ 𝑆)) ↔ (𝑆 ∈ (SubGrp‘𝐺) ∧ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆)))
36	3, 35	bitri 184	1 ⊢ (𝑆 ∈ (NrmSGrp‘𝐺) ↔ (𝑆 ∈ (SubGrp‘𝐺) ∧ ∀𝑥 ∈ 𝑋 ∀𝑦 ∈ 𝑋 ((𝑥 + 𝑦) ∈ 𝑆 → (𝑦 + 𝑥) ∈ 𝑆)))

Syntax hints:   → wi 4   ∧ wa 104   ↔ wb 105   = wceq 1395   ∈ wcel 2200  ∀wral 2508  ‘cfv 5314  (class class class)co 5994  Basecbs 13018  +_gcplusg 13096  SubGrpcsubg 13690  NrmSGrpcnsg 13691

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 714  ax-5 1493  ax-7 1494  ax-gen 1495  ax-ie1 1539  ax-ie2 1540  ax-8 1550  ax-10 1551  ax-11 1552  ax-i12 1553  ax-bndl 1555  ax-4 1556  ax-17 1572  ax-i9 1576  ax-ial 1580  ax-i5r 1581  ax-13 2202  ax-14 2203  ax-ext 2211  ax-sep 4201  ax-pow 4257  ax-pr 4292  ax-un 4521  ax-cnex 8078  ax-resscn 8079  ax-1re 8081  ax-addrcl 8084

This theorem depends on definitions:  df-bi 117  df-3an 1004  df-tru 1398  df-nf 1507  df-sb 1809  df-eu 2080  df-mo 2081  df-clab 2216  df-cleq 2222  df-clel 2225  df-nfc 2361  df-ral 2513  df-rex 2514  df-rab 2517  df-v 2801  df-sbc 3029  df-csb 3125  df-un 3201  df-in 3203  df-ss 3210  df-pw 3651  df-sn 3672  df-pr 3673  df-op 3675  df-uni 3888  df-int 3923  df-br 4083  df-opab 4145  df-mpt 4146  df-id 4381  df-xp 4722  df-rel 4723  df-cnv 4724  df-co 4725  df-dm 4726  df-rn 4727  df-res 4728  df-ima 4729  df-iota 5274  df-fun 5316  df-fn 5317  df-fv 5322  df-ov 5997  df-inn 9099  df-2 9157  df-ndx 13021  df-slot 13022  df-base 13024  df-plusg 13109  df-subg 13693  df-nsg 13694

This theorem is referenced by:  isnsg3  13730  subrngringnsg  14154