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Theorem fuchom 17469

Description: The morphisms in the functor category are natural transformations. (Contributed by Mario Carneiro, 6-Jan-2017.) (Proof shortened by AV, 14-Oct-2024.)

**Hypotheses**
Ref	Expression
fucbas.q	⊢ 𝑄 = (𝐶 FuncCat 𝐷)
fuchom.n	⊢ 𝑁 = (𝐶 Nat 𝐷)

**Assertion**
Ref	Expression
fuchom	⊢ 𝑁 = (Hom ‘𝑄)

Proof of Theorem fuchom Dummy variables 𝑎 𝑏 𝑓 𝑔 ℎ 𝑣 𝑥 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		fucbas.q	. . . . 5 ⊢ 𝑄 = (𝐶 FuncCat 𝐷)
2		eqid 2737	. . . . 5 ⊢ (𝐶 Func 𝐷) = (𝐶 Func 𝐷)
3		fuchom.n	. . . . 5 ⊢ 𝑁 = (𝐶 Nat 𝐷)
4		eqid 2737	. . . . 5 ⊢ (Base‘𝐶) = (Base‘𝐶)
5		eqid 2737	. . . . 5 ⊢ (comp‘𝐷) = (comp‘𝐷)
6		simpl 486	. . . . 5 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝐶 ∈ Cat)
7		simpr 488	. . . . 5 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝐷 ∈ Cat)
8		eqid 2737	. . . . . 6 ⊢ (comp‘𝑄) = (comp‘𝑄)
9	1, 2, 3, 4, 5, 6, 7, 8	fuccofval 17467	. . . . 5 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → (comp‘𝑄) = (𝑣 ∈ ((𝐶 Func 𝐷) × (𝐶 Func 𝐷)), ℎ ∈ (𝐶 Func 𝐷) ↦ ⦋(1^st ‘𝑣) / 𝑓⦌⦋(2^nd ‘𝑣) / 𝑔⦌(𝑏 ∈ (𝑔𝑁ℎ), 𝑎 ∈ (𝑓𝑁𝑔) ↦ (𝑥 ∈ (Base‘𝐶) ↦ ((𝑏‘𝑥)(⟨((1^st ‘𝑓)‘𝑥), ((1^st ‘𝑔)‘𝑥)⟩(comp‘𝐷)((1^st ‘ℎ)‘𝑥))(𝑎‘𝑥))))))
10	1, 2, 3, 4, 5, 6, 7, 9	fucval 17466	. . . 4 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑄 = {⟨(Base‘ndx), (𝐶 Func 𝐷)⟩, ⟨(Hom ‘ndx), 𝑁⟩, ⟨(comp‘ndx), (comp‘𝑄)⟩})
11		catstr 17465	. . . 4 ⊢ {⟨(Base‘ndx), (𝐶 Func 𝐷)⟩, ⟨(Hom ‘ndx), 𝑁⟩, ⟨(comp‘ndx), (comp‘𝑄)⟩} Struct ⟨1, ;15⟩
12		homid 16919	. . . 4 ⊢ Hom = Slot (Hom ‘ndx)
13		snsstp2 4730	. . . 4 ⊢ {⟨(Hom ‘ndx), 𝑁⟩} ⊆ {⟨(Base‘ndx), (𝐶 Func 𝐷)⟩, ⟨(Hom ‘ndx), 𝑁⟩, ⟨(comp‘ndx), (comp‘𝑄)⟩}
14	3	ovexi 7247	. . . . 5 ⊢ 𝑁 ∈ V
15	14	a1i 11	. . . 4 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑁 ∈ V)
16		eqid 2737	. . . 4 ⊢ (Hom ‘𝑄) = (Hom ‘𝑄)
17	10, 11, 12, 13, 15, 16	strfv3 16755	. . 3 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → (Hom ‘𝑄) = 𝑁)
18	17	eqcomd 2743	. 2 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑁 = (Hom ‘𝑄))
19	12	str0 16742	. . 3 ⊢ ∅ = (Hom ‘∅)
20	3	natffn 17456	. . . . 5 ⊢ 𝑁 Fn ((𝐶 Func 𝐷) × (𝐶 Func 𝐷))
21		funcrcl 17369	. . . . . . . . . 10 ⊢ (𝑓 ∈ (𝐶 Func 𝐷) → (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat))
22	21	con3i 157	. . . . . . . . 9 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → ¬ 𝑓 ∈ (𝐶 Func 𝐷))
23	22	eq0rdv 4319	. . . . . . . 8 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → (𝐶 Func 𝐷) = ∅)
24	23	xpeq2d 5581	. . . . . . 7 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → ((𝐶 Func 𝐷) × (𝐶 Func 𝐷)) = ((𝐶 Func 𝐷) × ∅))
25		xp0 6021	. . . . . . 7 ⊢ ((𝐶 Func 𝐷) × ∅) = ∅
26	24, 25	eqtrdi 2794	. . . . . 6 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → ((𝐶 Func 𝐷) × (𝐶 Func 𝐷)) = ∅)
27	26	fneq2d 6473	. . . . 5 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → (𝑁 Fn ((𝐶 Func 𝐷) × (𝐶 Func 𝐷)) ↔ 𝑁 Fn ∅))
28	20, 27	mpbii 236	. . . 4 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑁 Fn ∅)
29		fn0 6509	. . . 4 ⊢ (𝑁 Fn ∅ ↔ 𝑁 = ∅)
30	28, 29	sylib 221	. . 3 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑁 = ∅)
31		fnfuc 17452	. . . . . . 7 ⊢ FuncCat Fn (Cat × Cat)
32	31	fndmi 6482	. . . . . 6 ⊢ dom FuncCat = (Cat × Cat)
33	32	ndmov 7392	. . . . 5 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → (𝐶 FuncCat 𝐷) = ∅)
34	1, 33	syl5eq 2790	. . . 4 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑄 = ∅)
35	34	fveq2d 6721	. . 3 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → (Hom ‘𝑄) = (Hom ‘∅))
36	19, 30, 35	3eqtr4a 2804	. 2 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑁 = (Hom ‘𝑄))
37	18, 36	pm2.61i 185	1 ⊢ 𝑁 = (Hom ‘𝑄)

Colors of variables: wff setvar class

Syntax hints: ¬ wn 3 ∧ wa 399 = wceq 1543 ∈ wcel 2110 Vcvv 3408 ∅c0 4237 {ctp 4545 ⟨cop 4547 × cxp 5549 Fn wfn 6375 ‘cfv 6380 (class class class)co 7213 1c1 10730 5c5 11888 cdc 12293 ndxcnx 16744 Basecbs 16760 Hom chom 16813 compcco 16814 Catccat 17167 Func cfunc 17360 Nat cnat 17448 FuncCat cfuc 17449

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1803 ax-4 1817 ax-5 1918 ax-6 1976 ax-7 2016 ax-8 2112 ax-9 2120 ax-10 2141 ax-11 2158 ax-12 2175 ax-ext 2708 ax-rep 5179 ax-sep 5192 ax-nul 5199 ax-pow 5258 ax-pr 5322 ax-un 7523 ax-cnex 10785 ax-resscn 10786 ax-1cn 10787 ax-icn 10788 ax-addcl 10789 ax-addrcl 10790 ax-mulcl 10791 ax-mulrcl 10792 ax-mulcom 10793 ax-addass 10794 ax-mulass 10795 ax-distr 10796 ax-i2m1 10797 ax-1ne0 10798 ax-1rid 10799 ax-rnegex 10800 ax-rrecex 10801 ax-cnre 10802 ax-pre-lttri 10803 ax-pre-lttrn 10804 ax-pre-ltadd 10805 ax-pre-mulgt0 10806

This theorem depends on definitions: df-bi 210 df-an 400 df-or 848 df-3or 1090 df-3an 1091 df-tru 1546 df-fal 1556 df-ex 1788 df-nf 1792 df-sb 2071 df-mo 2539 df-eu 2568 df-clab 2715 df-cleq 2729 df-clel 2816 df-nfc 2886 df-ne 2941 df-nel 3047 df-ral 3066 df-rex 3067 df-reu 3068 df-rab 3070 df-v 3410 df-sbc 3695 df-csb 3812 df-dif 3869 df-un 3871 df-in 3873 df-ss 3883 df-pss 3885 df-nul 4238 df-if 4440 df-pw 4515 df-sn 4542 df-pr 4544 df-tp 4546 df-op 4548 df-uni 4820 df-iun 4906 df-br 5054 df-opab 5116 df-mpt 5136 df-tr 5162 df-id 5455 df-eprel 5460 df-po 5468 df-so 5469 df-fr 5509 df-we 5511 df-xp 5557 df-rel 5558 df-cnv 5559 df-co 5560 df-dm 5561 df-rn 5562 df-res 5563 df-ima 5564 df-pred 6160 df-ord 6216 df-on 6217 df-lim 6218 df-suc 6219 df-iota 6338 df-fun 6382 df-fn 6383 df-f 6384 df-f1 6385 df-fo 6386 df-f1o 6387 df-fv 6388 df-riota 7170 df-ov 7216 df-oprab 7217 df-mpo 7218 df-om 7645 df-1st 7761 df-2nd 7762 df-wrecs 8047 df-recs 8108 df-rdg 8146 df-1o 8202 df-er 8391 df-ixp 8579 df-en 8627 df-dom 8628 df-sdom 8629 df-fin 8630 df-pnf 10869 df-mnf 10870 df-xr 10871 df-ltxr 10872 df-le 10873 df-sub 11064 df-neg 11065 df-nn 11831 df-2 11893 df-3 11894 df-4 11895 df-5 11896 df-6 11897 df-7 11898 df-8 11899 df-9 11900 df-n0 12091 df-z 12177 df-dec 12294 df-uz 12439 df-fz 13096 df-struct 16700 df-slot 16735 df-ndx 16745 df-base 16761 df-hom 16826 df-cco 16827 df-func 17364 df-nat 17450 df-fuc 17451

This theorem is referenced by: fuccatid 17478 fucsect 17481 fuciso 17484 evlfcllem 17729 evlfcl 17730 curfcl 17740 uncf2 17745 curfuncf 17746 diag2cl 17754 curf2ndf 17755 yonedalem21 17781 yonedalem22 17786 yonedalem3b 17787 yonedalem3 17788 yonffthlem 17790

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