Theorem kerf1hrm 18566

Description: A ring homomorphism 𝐹 is injective if and only if its kernel is the singleton {𝑁}. (Contributed by Thierry Arnoux, 27-Oct-2017.) (Proof shortened by AV, 24-Oct-2019.)

Hypotheses

Ref	Expression
kerf1hrm.a	⊢ 𝐴 = (Base‘𝑅)
kerf1hrm.b	⊢ 𝐵 = (Base‘𝑆)
kerf1hrm.n	⊢ 𝑁 = (0g‘𝑅)
kerf1hrm.0	⊢ 0 = (0g‘𝑆)

Assertion

Ref	Expression
kerf1hrm	⊢ (𝐹 ∈ (𝑅 RingHom 𝑆) → (𝐹:𝐴–1-1→𝐵 ↔ (◡𝐹 “ { 0 }) = {𝑁}))

Proof of Theorem kerf1hrm

Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		simpl 472	. . . . . . 7 ⊢ (((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) ∧ 𝑥 ∈ (◡𝐹 “ { 0 })) → (𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵))
2		f1fn 6015	. . . . . . . . . . 11 ⊢ (𝐹:𝐴–1-1→𝐵 → 𝐹 Fn 𝐴)
3	2	adantl 481	. . . . . . . . . 10 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) → 𝐹 Fn 𝐴)
4		elpreima 6245	. . . . . . . . . 10 ⊢ (𝐹 Fn 𝐴 → (𝑥 ∈ (◡𝐹 “ { 0 }) ↔ (𝑥 ∈ 𝐴 ∧ (𝐹‘𝑥) ∈ { 0 })))
5	3, 4	syl 17	. . . . . . . . 9 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) → (𝑥 ∈ (◡𝐹 “ { 0 }) ↔ (𝑥 ∈ 𝐴 ∧ (𝐹‘𝑥) ∈ { 0 })))
6	5	biimpa 500	. . . . . . . 8 ⊢ (((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) ∧ 𝑥 ∈ (◡𝐹 “ { 0 })) → (𝑥 ∈ 𝐴 ∧ (𝐹‘𝑥) ∈ { 0 }))
7	6	simpld 474	. . . . . . 7 ⊢ (((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) ∧ 𝑥 ∈ (◡𝐹 “ { 0 })) → 𝑥 ∈ 𝐴)
8	6	simprd 478	. . . . . . . 8 ⊢ (((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) ∧ 𝑥 ∈ (◡𝐹 “ { 0 })) → (𝐹‘𝑥) ∈ { 0 })
9		fvex 6113	. . . . . . . . 9 ⊢ (𝐹‘𝑥) ∈ V
10	9	elsn 4140	. . . . . . . 8 ⊢ ((𝐹‘𝑥) ∈ { 0 } ↔ (𝐹‘𝑥) = 0 )
11	8, 10	sylib 207	. . . . . . 7 ⊢ (((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) ∧ 𝑥 ∈ (◡𝐹 “ { 0 })) → (𝐹‘𝑥) = 0 )
12		kerf1hrm.a	. . . . . . . . . . 11 ⊢ 𝐴 = (Base‘𝑅)
13		kerf1hrm.b	. . . . . . . . . . 11 ⊢ 𝐵 = (Base‘𝑆)
14		kerf1hrm.0	. . . . . . . . . . 11 ⊢ 0 = (0g‘𝑆)
15		kerf1hrm.n	. . . . . . . . . . 11 ⊢ 𝑁 = (0g‘𝑅)
16	12, 13, 14, 15	f1rhm0to0 18563	. . . . . . . . . 10 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵 ∧ 𝑥 ∈ 𝐴) → ((𝐹‘𝑥) = 0 ↔ 𝑥 = 𝑁))
17	16	biimpd 218	. . . . . . . . 9 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵 ∧ 𝑥 ∈ 𝐴) → ((𝐹‘𝑥) = 0 → 𝑥 = 𝑁))
18	17	3expa 1257	. . . . . . . 8 ⊢ (((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) ∧ 𝑥 ∈ 𝐴) → ((𝐹‘𝑥) = 0 → 𝑥 = 𝑁))
19	18	imp 444	. . . . . . 7 ⊢ ((((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) ∧ 𝑥 ∈ 𝐴) ∧ (𝐹‘𝑥) = 0 ) → 𝑥 = 𝑁)
20	1, 7, 11, 19	syl21anc 1317	. . . . . 6 ⊢ (((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) ∧ 𝑥 ∈ (◡𝐹 “ { 0 })) → 𝑥 = 𝑁)
21	20	ex 449	. . . . 5 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) → (𝑥 ∈ (◡𝐹 “ { 0 }) → 𝑥 = 𝑁))
22		velsn 4141	. . . . 5 ⊢ (𝑥 ∈ {𝑁} ↔ 𝑥 = 𝑁)
23	21, 22	syl6ibr 241	. . . 4 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) → (𝑥 ∈ (◡𝐹 “ { 0 }) → 𝑥 ∈ {𝑁}))
24	23	ssrdv 3574	. . 3 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) → (◡𝐹 “ { 0 }) ⊆ {𝑁})
25		rhmrcl1 18542	. . . . . . 7 ⊢ (𝐹 ∈ (𝑅 RingHom 𝑆) → 𝑅 ∈ Ring)
26		ringgrp 18375	. . . . . . 7 ⊢ (𝑅 ∈ Ring → 𝑅 ∈ Grp)
27	12, 15	grpidcl 17273	. . . . . . 7 ⊢ (𝑅 ∈ Grp → 𝑁 ∈ 𝐴)
28	25, 26, 27	3syl 18	. . . . . 6 ⊢ (𝐹 ∈ (𝑅 RingHom 𝑆) → 𝑁 ∈ 𝐴)
29		rhmghm 18548	. . . . . . . 8 ⊢ (𝐹 ∈ (𝑅 RingHom 𝑆) → 𝐹 ∈ (𝑅 GrpHom 𝑆))
30	15, 14	ghmid 17489	. . . . . . . 8 ⊢ (𝐹 ∈ (𝑅 GrpHom 𝑆) → (𝐹‘𝑁) = 0 )
31	29, 30	syl 17	. . . . . . 7 ⊢ (𝐹 ∈ (𝑅 RingHom 𝑆) → (𝐹‘𝑁) = 0 )
32		fvex 6113	. . . . . . . 8 ⊢ (𝐹‘𝑁) ∈ V
33	32	elsn 4140	. . . . . . 7 ⊢ ((𝐹‘𝑁) ∈ { 0 } ↔ (𝐹‘𝑁) = 0 )
34	31, 33	sylibr 223	. . . . . 6 ⊢ (𝐹 ∈ (𝑅 RingHom 𝑆) → (𝐹‘𝑁) ∈ { 0 })
35	12, 13	rhmf 18549	. . . . . . 7 ⊢ (𝐹 ∈ (𝑅 RingHom 𝑆) → 𝐹:𝐴⟶𝐵)
36		ffn 5958	. . . . . . 7 ⊢ (𝐹:𝐴⟶𝐵 → 𝐹 Fn 𝐴)
37		elpreima 6245	. . . . . . 7 ⊢ (𝐹 Fn 𝐴 → (𝑁 ∈ (◡𝐹 “ { 0 }) ↔ (𝑁 ∈ 𝐴 ∧ (𝐹‘𝑁) ∈ { 0 })))
38	35, 36, 37	3syl 18	. . . . . 6 ⊢ (𝐹 ∈ (𝑅 RingHom 𝑆) → (𝑁 ∈ (◡𝐹 “ { 0 }) ↔ (𝑁 ∈ 𝐴 ∧ (𝐹‘𝑁) ∈ { 0 })))
39	28, 34, 38	mpbir2and 959	. . . . 5 ⊢ (𝐹 ∈ (𝑅 RingHom 𝑆) → 𝑁 ∈ (◡𝐹 “ { 0 }))
40	39	snssd 4281	. . . 4 ⊢ (𝐹 ∈ (𝑅 RingHom 𝑆) → {𝑁} ⊆ (◡𝐹 “ { 0 }))
41	40	adantr 480	. . 3 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) → {𝑁} ⊆ (◡𝐹 “ { 0 }))
42	24, 41	eqssd 3585	. 2 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ 𝐹:𝐴–1-1→𝐵) → (◡𝐹 “ { 0 }) = {𝑁})
43	35	adantr 480	. . 3 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ (◡𝐹 “ { 0 }) = {𝑁}) → 𝐹:𝐴⟶𝐵)
44	29	adantr 480	. . . . . . . . . 10 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → 𝐹 ∈ (𝑅 GrpHom 𝑆))
45		simpr2l 1113	. . . . . . . . . 10 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → 𝑥 ∈ 𝐴)
46		simpr2r 1114	. . . . . . . . . 10 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → 𝑦 ∈ 𝐴)
47		simpr3 1062	. . . . . . . . . 10 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → (𝐹‘𝑥) = (𝐹‘𝑦))
48		eqid 2610	. . . . . . . . . . . 12 ⊢ (◡𝐹 “ { 0 }) = (◡𝐹 “ { 0 })
49		eqid 2610	. . . . . . . . . . . 12 ⊢ (-g‘𝑅) = (-g‘𝑅)
50	12, 14, 48, 49	ghmeqker 17510	. . . . . . . . . . 11 ⊢ ((𝐹 ∈ (𝑅 GrpHom 𝑆) ∧ 𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) → ((𝐹‘𝑥) = (𝐹‘𝑦) ↔ (𝑥(-g‘𝑅)𝑦) ∈ (◡𝐹 “ { 0 })))
51	50	biimpa 500	. . . . . . . . . 10 ⊢ (((𝐹 ∈ (𝑅 GrpHom 𝑆) ∧ 𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦)) → (𝑥(-g‘𝑅)𝑦) ∈ (◡𝐹 “ { 0 }))
52	44, 45, 46, 47, 51	syl31anc 1321	. . . . . . . . 9 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → (𝑥(-g‘𝑅)𝑦) ∈ (◡𝐹 “ { 0 }))
53		simpr1 1060	. . . . . . . . 9 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → (◡𝐹 “ { 0 }) = {𝑁})
54	52, 53	eleqtrd 2690	. . . . . . . 8 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → (𝑥(-g‘𝑅)𝑦) ∈ {𝑁})
55		ovex 6577	. . . . . . . . 9 ⊢ (𝑥(-g‘𝑅)𝑦) ∈ V
56	55	elsn 4140	. . . . . . . 8 ⊢ ((𝑥(-g‘𝑅)𝑦) ∈ {𝑁} ↔ (𝑥(-g‘𝑅)𝑦) = 𝑁)
57	54, 56	sylib 207	. . . . . . 7 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → (𝑥(-g‘𝑅)𝑦) = 𝑁)
58	25	adantr 480	. . . . . . . . 9 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → 𝑅 ∈ Ring)
59	58, 26	syl 17	. . . . . . . 8 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → 𝑅 ∈ Grp)
60	12, 15, 49	grpsubeq0 17324	. . . . . . . 8 ⊢ ((𝑅 ∈ Grp ∧ 𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) → ((𝑥(-g‘𝑅)𝑦) = 𝑁 ↔ 𝑥 = 𝑦))
61	59, 45, 46, 60	syl3anc 1318	. . . . . . 7 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → ((𝑥(-g‘𝑅)𝑦) = 𝑁 ↔ 𝑥 = 𝑦))
62	57, 61	mpbid 221	. . . . . 6 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ ((◡𝐹 “ { 0 }) = {𝑁} ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) ∧ (𝐹‘𝑥) = (𝐹‘𝑦))) → 𝑥 = 𝑦)
63	62	3anassrs 1282	. . . . 5 ⊢ ((((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ (◡𝐹 “ { 0 }) = {𝑁}) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) ∧ (𝐹‘𝑥) = (𝐹‘𝑦)) → 𝑥 = 𝑦)
64	63	ex 449	. . . 4 ⊢ (((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ (◡𝐹 “ { 0 }) = {𝑁}) ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → ((𝐹‘𝑥) = (𝐹‘𝑦) → 𝑥 = 𝑦))
65	64	ralrimivva 2954	. . 3 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ (◡𝐹 “ { 0 }) = {𝑁}) → ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 ((𝐹‘𝑥) = (𝐹‘𝑦) → 𝑥 = 𝑦))
66		dff13 6416	. . 3 ⊢ (𝐹:𝐴–1-1→𝐵 ↔ (𝐹:𝐴⟶𝐵 ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 ((𝐹‘𝑥) = (𝐹‘𝑦) → 𝑥 = 𝑦)))
67	43, 65, 66	sylanbrc 695	. 2 ⊢ ((𝐹 ∈ (𝑅 RingHom 𝑆) ∧ (◡𝐹 “ { 0 }) = {𝑁}) → 𝐹:𝐴–1-1→𝐵)
68	42, 67	impbida 873	1 ⊢ (𝐹 ∈ (𝑅 RingHom 𝑆) → (𝐹:𝐴–1-1→𝐵 ↔ (◡𝐹 “ { 0 }) = {𝑁}))

Syntax hints:   → wi 4   ↔ wb 195   ∧ wa 383   ∧ w3a 1031   = wceq 1475   ∈ wcel 1977  ∀wral 2896   ⊆ wss 3540  {csn 4125  ^◡ccnv 5037   “ cima 5041   Fn wfn 5799  ⟶wf 5800  –1-1→wf1 5801  ‘cfv 5804  (class class class)co 6549  Basecbs 15695  0_gc0g 15923  Grpcgrp 17245  -_gcsg 17247   GrpHom cghm 17480  Ringcrg 18370   RingHom crh 18535

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-8 1979  ax-9 1986  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590  ax-rep 4699  ax-sep 4709  ax-nul 4717  ax-pow 4769  ax-pr 4833  ax-un 6847  ax-cnex 9871  ax-resscn 9872  ax-1cn 9873  ax-icn 9874  ax-addcl 9875  ax-addrcl 9876  ax-mulcl 9877  ax-mulrcl 9878  ax-mulcom 9879  ax-addass 9880  ax-mulass 9881  ax-distr 9882  ax-i2m1 9883  ax-1ne0 9884  ax-1rid 9885  ax-rnegex 9886  ax-rrecex 9887  ax-cnre 9888  ax-pre-lttri 9889  ax-pre-lttrn 9890  ax-pre-ltadd 9891  ax-pre-mulgt0 9892

This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-3or 1032  df-3an 1033  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-eu 2462  df-mo 2463  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-ne 2782  df-nel 2783  df-ral 2901  df-rex 2902  df-reu 2903  df-rmo 2904  df-rab 2905  df-v 3175  df-sbc 3403  df-csb 3500  df-dif 3543  df-un 3545  df-in 3547  df-ss 3554  df-pss 3556  df-nul 3875  df-if 4037  df-pw 4110  df-sn 4126  df-pr 4128  df-tp 4130  df-op 4132  df-uni 4373  df-iun 4457  df-br 4584  df-opab 4644  df-mpt 4645  df-tr 4681  df-eprel 4949  df-id 4953  df-po 4959  df-so 4960  df-fr 4997  df-we 4999  df-xp 5044  df-rel 5045  df-cnv 5046  df-co 5047  df-dm 5048  df-rn 5049  df-res 5050  df-ima 5051  df-pred 5597  df-ord 5643  df-on 5644  df-lim 5645  df-suc 5646  df-iota 5768  df-fun 5806  df-fn 5807  df-f 5808  df-f1 5809  df-fo 5810  df-f1o 5811  df-fv 5812  df-riota 6511  df-ov 6552  df-oprab 6553  df-mpt2 6554  df-om 6958  df-1st 7059  df-2nd 7060  df-wrecs 7294  df-recs 7355  df-rdg 7393  df-er 7629  df-map 7746  df-en 7842  df-dom 7843  df-sdom 7844  df-pnf 9955  df-mnf 9956  df-xr 9957  df-ltxr 9958  df-le 9959  df-sub 10147  df-neg 10148  df-nn 10898  df-2 10956  df-ndx 15698  df-slot 15699  df-base 15700  df-sets 15701  df-plusg 15781  df-0g 15925  df-mgm 17065  df-sgrp 17107  df-mnd 17118  df-mhm 17158  df-grp 17248  df-minusg 17249  df-sbg 17250  df-ghm 17481  df-mgp 18313  df-ur 18325  df-ring 18372  df-rnghom 18538

This theorem is referenced by:  zrhf1ker  29347