Theorem idghm 17992

Description: The identity homomorphism on a group. (Contributed by Stefan O'Rear, 31-Dec-2014.)

Hypothesis

Ref	Expression
idghm.b	⊢ 𝐵 = (Base‘𝐺)

Assertion

Ref	Expression
idghm	⊢ (𝐺 ∈ Grp → ( I ↾ 𝐵) ∈ (𝐺 GrpHom 𝐺))

Proof of Theorem idghm

Dummy variables 𝑎 𝑏 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		id 22	. . 3 ⊢ (𝐺 ∈ Grp → 𝐺 ∈ Grp)
2	1	ancli 545	. 2 ⊢ (𝐺 ∈ Grp → (𝐺 ∈ Grp ∧ 𝐺 ∈ Grp))
3		idghm.b	. . . . . . . 8 ⊢ 𝐵 = (Base‘𝐺)
4		eqid 2803	. . . . . . . 8 ⊢ (+g‘𝐺) = (+g‘𝐺)
5	3, 4	grpcl 17750	. . . . . . 7 ⊢ ((𝐺 ∈ Grp ∧ 𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵) → (𝑎(+g‘𝐺)𝑏) ∈ 𝐵)
6	5	3expb 1150	. . . . . 6 ⊢ ((𝐺 ∈ Grp ∧ (𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵)) → (𝑎(+g‘𝐺)𝑏) ∈ 𝐵)
7		fvresi 6672	. . . . . 6 ⊢ ((𝑎(+g‘𝐺)𝑏) ∈ 𝐵 → (( I ↾ 𝐵)‘(𝑎(+g‘𝐺)𝑏)) = (𝑎(+g‘𝐺)𝑏))
8	6, 7	syl 17	. . . . 5 ⊢ ((𝐺 ∈ Grp ∧ (𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵)) → (( I ↾ 𝐵)‘(𝑎(+g‘𝐺)𝑏)) = (𝑎(+g‘𝐺)𝑏))
9		fvresi 6672	. . . . . . 7 ⊢ (𝑎 ∈ 𝐵 → (( I ↾ 𝐵)‘𝑎) = 𝑎)
10		fvresi 6672	. . . . . . 7 ⊢ (𝑏 ∈ 𝐵 → (( I ↾ 𝐵)‘𝑏) = 𝑏)
11	9, 10	oveqan12d 6901	. . . . . 6 ⊢ ((𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵) → ((( I ↾ 𝐵)‘𝑎)(+g‘𝐺)(( I ↾ 𝐵)‘𝑏)) = (𝑎(+g‘𝐺)𝑏))
12	11	adantl 474	. . . . 5 ⊢ ((𝐺 ∈ Grp ∧ (𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵)) → ((( I ↾ 𝐵)‘𝑎)(+g‘𝐺)(( I ↾ 𝐵)‘𝑏)) = (𝑎(+g‘𝐺)𝑏))
13	8, 12	eqtr4d 2840	. . . 4 ⊢ ((𝐺 ∈ Grp ∧ (𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵)) → (( I ↾ 𝐵)‘(𝑎(+g‘𝐺)𝑏)) = ((( I ↾ 𝐵)‘𝑎)(+g‘𝐺)(( I ↾ 𝐵)‘𝑏)))
14	13	ralrimivva 3156	. . 3 ⊢ (𝐺 ∈ Grp → ∀𝑎 ∈ 𝐵 ∀𝑏 ∈ 𝐵 (( I ↾ 𝐵)‘(𝑎(+g‘𝐺)𝑏)) = ((( I ↾ 𝐵)‘𝑎)(+g‘𝐺)(( I ↾ 𝐵)‘𝑏)))
15		f1oi 6397	. . . 4 ⊢ ( I ↾ 𝐵):𝐵–1-1-onto→𝐵
16		f1of 6360	. . . 4 ⊢ (( I ↾ 𝐵):𝐵–1-1-onto→𝐵 → ( I ↾ 𝐵):𝐵⟶𝐵)
17	15, 16	ax-mp 5	. . 3 ⊢ ( I ↾ 𝐵):𝐵⟶𝐵
18	14, 17	jctil 516	. 2 ⊢ (𝐺 ∈ Grp → (( I ↾ 𝐵):𝐵⟶𝐵 ∧ ∀𝑎 ∈ 𝐵 ∀𝑏 ∈ 𝐵 (( I ↾ 𝐵)‘(𝑎(+g‘𝐺)𝑏)) = ((( I ↾ 𝐵)‘𝑎)(+g‘𝐺)(( I ↾ 𝐵)‘𝑏))))
19	3, 3, 4, 4	isghm 17977	. 2 ⊢ (( I ↾ 𝐵) ∈ (𝐺 GrpHom 𝐺) ↔ ((𝐺 ∈ Grp ∧ 𝐺 ∈ Grp) ∧ (( I ↾ 𝐵):𝐵⟶𝐵 ∧ ∀𝑎 ∈ 𝐵 ∀𝑏 ∈ 𝐵 (( I ↾ 𝐵)‘(𝑎(+g‘𝐺)𝑏)) = ((( I ↾ 𝐵)‘𝑎)(+g‘𝐺)(( I ↾ 𝐵)‘𝑏)))))
20	2, 18, 19	sylanbrc 579	1 ⊢ (𝐺 ∈ Grp → ( I ↾ 𝐵) ∈ (𝐺 GrpHom 𝐺))

Syntax hints:   → wi 4   ∧ wa 385   = wceq 1653   ∈ wcel 2157  ∀wral 3093   I cid 5223   ↾ cres 5318  ⟶wf 6101  –1-1-onto→wf1o 6104  ‘cfv 6105  (class class class)co 6882  Basecbs 16188  +_gcplusg 16271  Grpcgrp 17742   GrpHom cghm 17974

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1891  ax-4 1905  ax-5 2006  ax-6 2072  ax-7 2107  ax-8 2159  ax-9 2166  ax-10 2185  ax-11 2200  ax-12 2213  ax-13 2379  ax-ext 2781  ax-rep 4968  ax-sep 4979  ax-nul 4987  ax-pow 5039  ax-pr 5101  ax-un 7187

This theorem depends on definitions:  df-bi 199  df-an 386  df-or 875  df-3an 1110  df-tru 1657  df-ex 1876  df-nf 1880  df-sb 2065  df-mo 2593  df-eu 2611  df-clab 2790  df-cleq 2796  df-clel 2799  df-nfc 2934  df-ne 2976  df-ral 3098  df-rex 3099  df-reu 3100  df-rab 3102  df-v 3391  df-sbc 3638  df-csb 3733  df-dif 3776  df-un 3778  df-in 3780  df-ss 3787  df-nul 4120  df-if 4282  df-pw 4355  df-sn 4373  df-pr 4375  df-op 4379  df-uni 4633  df-iun 4716  df-br 4848  df-opab 4910  df-mpt 4927  df-id 5224  df-xp 5322  df-rel 5323  df-cnv 5324  df-co 5325  df-dm 5326  df-rn 5327  df-res 5328  df-ima 5329  df-iota 6068  df-fun 6107  df-fn 6108  df-f 6109  df-f1 6110  df-fo 6111  df-f1o 6112  df-fv 6113  df-ov 6885  df-oprab 6886  df-mpt2 6887  df-mgm 17561  df-sgrp 17603  df-mnd 17614  df-grp 17745  df-ghm 17975

This theorem is referenced by:  gicref  18030  symgga  18142  0frgp  18511  idrhm  19053  idlmhm  19366  frgpcyg  20247  nmoid  22878  idnghm  22879  idrnghm  42711