idfu1 - Metamath Proof Explorer

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Theorem idfu1 18070

Description: Value of the object part of the identity functor. (Contributed by Mario Carneiro, 3-Jan-2017.)

**Hypotheses**
Ref	Expression
idfuval.i	⊢ 𝐼 = (id_func‘𝐶)
idfuval.b	⊢ 𝐵 = (Base‘𝐶)
idfuval.c	⊢ (𝜑 → 𝐶 ∈ Cat)
idfu1.x	⊢ (𝜑 → 𝑋 ∈ 𝐵)

**Assertion**
Ref	Expression
idfu1	⊢ (𝜑 → ((1^st ‘𝐼)‘𝑋) = 𝑋)

**Proof of Theorem idfu1**
Step	Hyp	Ref	Expression
1		idfuval.i	. . . 4 ⊢ 𝐼 = (id_func‘𝐶)
2		idfuval.b	. . . 4 ⊢ 𝐵 = (Base‘𝐶)
3		idfuval.c	. . . 4 ⊢ (𝜑 → 𝐶 ∈ Cat)
4	1, 2, 3	idfu1st 18069	. . 3 ⊢ (𝜑 → (1^st ‘𝐼) = ( I ↾ 𝐵))
5	4	fveq1d 6898	. 2 ⊢ (𝜑 → ((1^st ‘𝐼)‘𝑋) = (( I ↾ 𝐵)‘𝑋))
6		idfu1.x	. . 3 ⊢ (𝜑 → 𝑋 ∈ 𝐵)
7		fvresi 7188	. . 3 ⊢ (𝑋 ∈ 𝐵 → (( I ↾ 𝐵)‘𝑋) = 𝑋)
8	6, 7	syl 18	. 2 ⊢ (𝜑 → (( I ↾ 𝐵)‘𝑋) = 𝑋)
9	5, 8	eqtrd 2798	1 ⊢ (𝜑 → ((1^st ‘𝐼)‘𝑋) = 𝑋)

Colors of variables: wff setvar class

This proof depends on syntax axioms: → wi 4 = wceq 1569 ∈ wcel 2146 I cid 5549 ↾ cres 5657 ‘cfv 6547 1^st c1st 8009 Basecbs 17402 Catccat 17853 id_funccidfu 18045

This proof depends on axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1827 ax-4 1841 ax-5 1944 ax-6 2001 ax-7 2042 ax-8 2148 ax-9 2156 ax-10 2179 ax-11 2196 ax-12 2215 ax-ext 2735 ax-rep 5235 ax-sep 5252 ax-nul 5263 ax-pow 5331 ax-pr 5395 ax-un 7761

This proof depends on definitions: df-bi 210 df-an 402 df-or 862 df-3an 1105 df-tru 1572 df-fal 1582 df-ex 1812 df-nf 1816 df-sb 2101 df-mo 2567 df-eu 2597 df-clab 2742 df-cleq 2755 df-clel 2839 df-nfc 2913 df-ne 2960 df-ral 3081 df-rex 3091 df-reu 3370 df-rab 3417 df-v 3456 df-sbc 3743 df-csb 3852 df-ss 3901 df-dif 4050 df-in 4094 df-un 4154 df-nul 4282 df-if 4486 df-pw 4562 df-sn 4589 df-pr 4591 df-op 4839 df-uni 4871 df-iun 4956 df-br 5107 df-opab 5171 df-mpt 5190 df-id 5550 df-xp 5661 df-rel 5662 df-cnv 5663 df-co 5664 df-dm 5665 df-rn 5666 df-res 5667 df-ima 5668 df-iota 6501 df-fun 6549 df-fn 6550 df-f 6551 df-f1 6552 df-fo 6553 df-f1o 6554 df-fv 6555 df-1st 8011 df-idfu 18049

This theorem is used by: idffth 18125 ressffth 18130 catciso 18301 idfu1a 50363 cofid1a 50373

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