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Theorem fuchom 17909

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 2732	. . . . 5 ⊢ (𝐶 Func 𝐷) = (𝐶 Func 𝐷)
3		fuchom.n	. . . . 5 ⊢ 𝑁 = (𝐶 Nat 𝐷)
4		eqid 2732	. . . . 5 ⊢ (Base‘𝐶) = (Base‘𝐶)
5		eqid 2732	. . . . 5 ⊢ (comp‘𝐷) = (comp‘𝐷)
6		simpl 483	. . . . 5 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝐶 ∈ Cat)
7		simpr 485	. . . . 5 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝐷 ∈ Cat)
8		eqid 2732	. . . . . 6 ⊢ (comp‘𝑄) = (comp‘𝑄)
9	1, 2, 3, 4, 5, 6, 7, 8	fuccofval 17907	. . . . 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 17906	. . . 4 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑄 = {⟨(Base‘ndx), (𝐶 Func 𝐷)⟩, ⟨(Hom ‘ndx), 𝑁⟩, ⟨(comp‘ndx), (comp‘𝑄)⟩})
11		catstr 17905	. . . 4 ⊢ {⟨(Base‘ndx), (𝐶 Func 𝐷)⟩, ⟨(Hom ‘ndx), 𝑁⟩, ⟨(comp‘ndx), (comp‘𝑄)⟩} Struct ⟨1, ;15⟩
12		homid 17353	. . . 4 ⊢ Hom = Slot (Hom ‘ndx)
13		snsstp2 4819	. . . 4 ⊢ {⟨(Hom ‘ndx), 𝑁⟩} ⊆ {⟨(Base‘ndx), (𝐶 Func 𝐷)⟩, ⟨(Hom ‘ndx), 𝑁⟩, ⟨(comp‘ndx), (comp‘𝑄)⟩}
14	3	ovexi 7439	. . . . 5 ⊢ 𝑁 ∈ V
15	14	a1i 11	. . . 4 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑁 ∈ V)
16		eqid 2732	. . . 4 ⊢ (Hom ‘𝑄) = (Hom ‘𝑄)
17	10, 11, 12, 13, 15, 16	strfv3 17134	. . 3 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → (Hom ‘𝑄) = 𝑁)
18	17	eqcomd 2738	. 2 ⊢ ((𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑁 = (Hom ‘𝑄))
19	12	str0 17118	. . 3 ⊢ ∅ = (Hom ‘∅)
20	3	natffn 17896	. . . . 5 ⊢ 𝑁 Fn ((𝐶 Func 𝐷) × (𝐶 Func 𝐷))
21		funcrcl 17809	. . . . . . . . . 10 ⊢ (𝑓 ∈ (𝐶 Func 𝐷) → (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat))
22	21	con3i 154	. . . . . . . . 9 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → ¬ 𝑓 ∈ (𝐶 Func 𝐷))
23	22	eq0rdv 4403	. . . . . . . 8 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → (𝐶 Func 𝐷) = ∅)
24	23	xpeq2d 5705	. . . . . . 7 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → ((𝐶 Func 𝐷) × (𝐶 Func 𝐷)) = ((𝐶 Func 𝐷) × ∅))
25		xp0 6154	. . . . . . 7 ⊢ ((𝐶 Func 𝐷) × ∅) = ∅
26	24, 25	eqtrdi 2788	. . . . . 6 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → ((𝐶 Func 𝐷) × (𝐶 Func 𝐷)) = ∅)
27	26	fneq2d 6640	. . . . 5 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → (𝑁 Fn ((𝐶 Func 𝐷) × (𝐶 Func 𝐷)) ↔ 𝑁 Fn ∅))
28	20, 27	mpbii 232	. . . 4 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑁 Fn ∅)
29		fn0 6678	. . . 4 ⊢ (𝑁 Fn ∅ ↔ 𝑁 = ∅)
30	28, 29	sylib 217	. . 3 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑁 = ∅)
31		fnfuc 17892	. . . . . . 7 ⊢ FuncCat Fn (Cat × Cat)
32	31	fndmi 6650	. . . . . 6 ⊢ dom FuncCat = (Cat × Cat)
33	32	ndmov 7587	. . . . 5 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → (𝐶 FuncCat 𝐷) = ∅)
34	1, 33	eqtrid 2784	. . . 4 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑄 = ∅)
35	34	fveq2d 6892	. . 3 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → (Hom ‘𝑄) = (Hom ‘∅))
36	19, 30, 35	3eqtr4a 2798	. 2 ⊢ (¬ (𝐶 ∈ Cat ∧ 𝐷 ∈ Cat) → 𝑁 = (Hom ‘𝑄))
37	18, 36	pm2.61i 182	1 ⊢ 𝑁 = (Hom ‘𝑄)

Colors of variables: wff setvar class

Syntax hints: ¬ wn 3 ∧ wa 396 = wceq 1541 ∈ wcel 2106 Vcvv 3474 ∅c0 4321 {ctp 4631 ⟨cop 4633 × cxp 5673 Fn wfn 6535 ‘cfv 6540 (class class class)co 7405 1c1 11107 5c5 12266 cdc 12673 ndxcnx 17122 Basecbs 17140 Hom chom 17204 compcco 17205 Catccat 17604 Func cfunc 17800 Nat cnat 17888 FuncCat cfuc 17889

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1913 ax-6 1971 ax-7 2011 ax-8 2108 ax-9 2116 ax-10 2137 ax-11 2154 ax-12 2171 ax-ext 2703 ax-rep 5284 ax-sep 5298 ax-nul 5305 ax-pow 5362 ax-pr 5426 ax-un 7721 ax-cnex 11162 ax-resscn 11163 ax-1cn 11164 ax-icn 11165 ax-addcl 11166 ax-addrcl 11167 ax-mulcl 11168 ax-mulrcl 11169 ax-mulcom 11170 ax-addass 11171 ax-mulass 11172 ax-distr 11173 ax-i2m1 11174 ax-1ne0 11175 ax-1rid 11176 ax-rnegex 11177 ax-rrecex 11178 ax-cnre 11179 ax-pre-lttri 11180 ax-pre-lttrn 11181 ax-pre-ltadd 11182 ax-pre-mulgt0 11183

This theorem depends on definitions: df-bi 206 df-an 397 df-or 846 df-3or 1088 df-3an 1089 df-tru 1544 df-fal 1554 df-ex 1782 df-nf 1786 df-sb 2068 df-mo 2534 df-eu 2563 df-clab 2710 df-cleq 2724 df-clel 2810 df-nfc 2885 df-ne 2941 df-nel 3047 df-ral 3062 df-rex 3071 df-reu 3377 df-rab 3433 df-v 3476 df-sbc 3777 df-csb 3893 df-dif 3950 df-un 3952 df-in 3954 df-ss 3964 df-pss 3966 df-nul 4322 df-if 4528 df-pw 4603 df-sn 4628 df-pr 4630 df-tp 4632 df-op 4634 df-uni 4908 df-iun 4998 df-br 5148 df-opab 5210 df-mpt 5231 df-tr 5265 df-id 5573 df-eprel 5579 df-po 5587 df-so 5588 df-fr 5630 df-we 5632 df-xp 5681 df-rel 5682 df-cnv 5683 df-co 5684 df-dm 5685 df-rn 5686 df-res 5687 df-ima 5688 df-pred 6297 df-ord 6364 df-on 6365 df-lim 6366 df-suc 6367 df-iota 6492 df-fun 6542 df-fn 6543 df-f 6544 df-f1 6545 df-fo 6546 df-f1o 6547 df-fv 6548 df-riota 7361 df-ov 7408 df-oprab 7409 df-mpo 7410 df-om 7852 df-1st 7971 df-2nd 7972 df-frecs 8262 df-wrecs 8293 df-recs 8367 df-rdg 8406 df-1o 8462 df-er 8699 df-ixp 8888 df-en 8936 df-dom 8937 df-sdom 8938 df-fin 8939 df-pnf 11246 df-mnf 11247 df-xr 11248 df-ltxr 11249 df-le 11250 df-sub 11442 df-neg 11443 df-nn 12209 df-2 12271 df-3 12272 df-4 12273 df-5 12274 df-6 12275 df-7 12276 df-8 12277 df-9 12278 df-n0 12469 df-z 12555 df-dec 12674 df-uz 12819 df-fz 13481 df-struct 17076 df-slot 17111 df-ndx 17123 df-base 17141 df-hom 17217 df-cco 17218 df-func 17804 df-nat 17890 df-fuc 17891

This theorem is referenced by: fuccatid 17918 fucsect 17921 fuciso 17924 evlfcllem 18170 evlfcl 18171 curfcl 18181 uncf2 18186 curfuncf 18187 diag2cl 18195 curf2ndf 18196 yonedalem21 18222 yonedalem22 18227 yonedalem3b 18228 yonedalem3 18229 yonffthlem 18231

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