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Theorem initoeu1 17936
Description: Initial objects are essentially unique (strong form), i.e. there is a unique isomorphism between two initial objects, see statement in [Lang] p. 58 ("... if P, P' are two universal objects [...] then there exists a unique isomorphism between them.". (Proposed by BJ, 14-Apr-2020.) (Contributed by AV, 14-Apr-2020.)
Hypotheses
Ref Expression
initoeu1.c (𝜑𝐶 ∈ Cat)
initoeu1.a (𝜑𝐴 ∈ (InitO‘𝐶))
initoeu1.b (𝜑𝐵 ∈ (InitO‘𝐶))
Assertion
Ref Expression
initoeu1 (𝜑 → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))
Distinct variable groups:   𝐴,𝑓   𝐵,𝑓   𝐶,𝑓   𝜑,𝑓

Proof of Theorem initoeu1
Dummy variables 𝑎 𝑔 𝑏 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 initoeu1.a . . 3 (𝜑𝐴 ∈ (InitO‘𝐶))
2 eqid 2729 . . . 4 (Base‘𝐶) = (Base‘𝐶)
3 eqid 2729 . . . 4 (Hom ‘𝐶) = (Hom ‘𝐶)
4 initoeu1.c . . . 4 (𝜑𝐶 ∈ Cat)
52, 3, 4isinitoi 17924 . . 3 ((𝜑𝐴 ∈ (InitO‘𝐶)) → (𝐴 ∈ (Base‘𝐶) ∧ ∀𝑏 ∈ (Base‘𝐶)∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝑏)))
61, 5mpdan 687 . 2 (𝜑 → (𝐴 ∈ (Base‘𝐶) ∧ ∀𝑏 ∈ (Base‘𝐶)∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝑏)))
7 initoeu1.b . . . . 5 (𝜑𝐵 ∈ (InitO‘𝐶))
82, 3, 4isinitoi 17924 . . . . 5 ((𝜑𝐵 ∈ (InitO‘𝐶)) → (𝐵 ∈ (Base‘𝐶) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎)))
97, 8mpdan 687 . . . 4 (𝜑 → (𝐵 ∈ (Base‘𝐶) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎)))
10 oveq2 7361 . . . . . . . . . 10 (𝑏 = 𝐵 → (𝐴(Hom ‘𝐶)𝑏) = (𝐴(Hom ‘𝐶)𝐵))
1110eleq2d 2814 . . . . . . . . 9 (𝑏 = 𝐵 → (𝑓 ∈ (𝐴(Hom ‘𝐶)𝑏) ↔ 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵)))
1211eubidv 2579 . . . . . . . 8 (𝑏 = 𝐵 → (∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝑏) ↔ ∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵)))
1312rspcv 3575 . . . . . . 7 (𝐵 ∈ (Base‘𝐶) → (∀𝑏 ∈ (Base‘𝐶)∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝑏) → ∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵)))
14 eqid 2729 . . . . . . . . . . . . . 14 (Iso‘𝐶) = (Iso‘𝐶)
154adantr 480 . . . . . . . . . . . . . 14 ((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) → 𝐶 ∈ Cat)
16 simprr 772 . . . . . . . . . . . . . 14 ((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) → 𝐴 ∈ (Base‘𝐶))
17 simprl 770 . . . . . . . . . . . . . 14 ((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) → 𝐵 ∈ (Base‘𝐶))
182, 3, 14, 15, 16, 17isohom 17701 . . . . . . . . . . . . 13 ((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) → (𝐴(Iso‘𝐶)𝐵) ⊆ (𝐴(Hom ‘𝐶)𝐵))
1918adantr 480 . . . . . . . . . . . 12 (((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) ∧ (∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎))) → (𝐴(Iso‘𝐶)𝐵) ⊆ (𝐴(Hom ‘𝐶)𝐵))
20 euex 2570 . . . . . . . . . . . . . . 15 (∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) → ∃𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵))
2120a1i 11 . . . . . . . . . . . . . 14 ((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) → (∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) → ∃𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵)))
22 oveq2 7361 . . . . . . . . . . . . . . . . . . . 20 (𝑎 = 𝐴 → (𝐵(Hom ‘𝐶)𝑎) = (𝐵(Hom ‘𝐶)𝐴))
2322eleq2d 2814 . . . . . . . . . . . . . . . . . . 19 (𝑎 = 𝐴 → (𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎) ↔ 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)))
2423eubidv 2579 . . . . . . . . . . . . . . . . . 18 (𝑎 = 𝐴 → (∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎) ↔ ∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)))
2524rspcva 3577 . . . . . . . . . . . . . . . . 17 ((𝐴 ∈ (Base‘𝐶) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎)) → ∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴))
26 euex 2570 . . . . . . . . . . . . . . . . 17 (∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴) → ∃𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴))
2725, 26syl 17 . . . . . . . . . . . . . . . 16 ((𝐴 ∈ (Base‘𝐶) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎)) → ∃𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴))
2827ex 412 . . . . . . . . . . . . . . 15 (𝐴 ∈ (Base‘𝐶) → (∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎) → ∃𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)))
2928ad2antll 729 . . . . . . . . . . . . . 14 ((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) → (∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎) → ∃𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)))
30 eqid 2729 . . . . . . . . . . . . . . . . . . . . 21 (Inv‘𝐶) = (Inv‘𝐶)
3115ad2antrr 726 . . . . . . . . . . . . . . . . . . . . 21 ((((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) ∧ 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)) ∧ 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵)) → 𝐶 ∈ Cat)
3216ad2antrr 726 . . . . . . . . . . . . . . . . . . . . 21 ((((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) ∧ 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)) ∧ 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵)) → 𝐴 ∈ (Base‘𝐶))
3317ad2antrr 726 . . . . . . . . . . . . . . . . . . . . 21 ((((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) ∧ 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)) ∧ 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵)) → 𝐵 ∈ (Base‘𝐶))
344, 1, 72initoinv 17935 . . . . . . . . . . . . . . . . . . . . . 22 ((𝜑𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴) ∧ 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵)) → 𝑓(𝐴(Inv‘𝐶)𝐵)𝑔)
3534ad4ant134 1175 . . . . . . . . . . . . . . . . . . . . 21 ((((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) ∧ 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)) ∧ 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵)) → 𝑓(𝐴(Inv‘𝐶)𝐵)𝑔)
362, 30, 31, 32, 33, 14, 35inviso1 17691 . . . . . . . . . . . . . . . . . . . 20 ((((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) ∧ 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)) ∧ 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵)) → 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))
3736ex 412 . . . . . . . . . . . . . . . . . . 19 (((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) ∧ 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)) → (𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) → 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵)))
3837eximdv 1917 . . . . . . . . . . . . . . . . . 18 (((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) ∧ 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)) → (∃𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) → ∃𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵)))
3938expcom 413 . . . . . . . . . . . . . . . . 17 (𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴) → ((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) → (∃𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) → ∃𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))))
4039exlimiv 1930 . . . . . . . . . . . . . . . 16 (∃𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴) → ((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) → (∃𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) → ∃𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))))
4140com3l 89 . . . . . . . . . . . . . . 15 ((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) → (∃𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) → (∃𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴) → ∃𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))))
4241impd 410 . . . . . . . . . . . . . 14 ((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) → ((∃𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) ∧ ∃𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝐴)) → ∃𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵)))
4321, 29, 42syl2and 608 . . . . . . . . . . . . 13 ((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) → ((∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎)) → ∃𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵)))
4443imp 406 . . . . . . . . . . . 12 (((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) ∧ (∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎))) → ∃𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))
45 simprl 770 . . . . . . . . . . . 12 (((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) ∧ (∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎))) → ∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵))
46 euelss 4285 . . . . . . . . . . . 12 (((𝐴(Iso‘𝐶)𝐵) ⊆ (𝐴(Hom ‘𝐶)𝐵) ∧ ∃𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵) ∧ ∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵)) → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))
4719, 44, 45, 46syl3anc 1373 . . . . . . . . . . 11 (((𝜑 ∧ (𝐵 ∈ (Base‘𝐶) ∧ 𝐴 ∈ (Base‘𝐶))) ∧ (∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎))) → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))
4847exp42 435 . . . . . . . . . 10 (𝜑 → (𝐵 ∈ (Base‘𝐶) → (𝐴 ∈ (Base‘𝐶) → ((∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎)) → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵)))))
4948com24 95 . . . . . . . . 9 (𝜑 → ((∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎)) → (𝐴 ∈ (Base‘𝐶) → (𝐵 ∈ (Base‘𝐶) → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵)))))
5049com14 96 . . . . . . . 8 (𝐵 ∈ (Base‘𝐶) → ((∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎)) → (𝐴 ∈ (Base‘𝐶) → (𝜑 → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵)))))
5150expd 415 . . . . . . 7 (𝐵 ∈ (Base‘𝐶) → (∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝐵) → (∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎) → (𝐴 ∈ (Base‘𝐶) → (𝜑 → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))))))
5213, 51syldc 48 . . . . . 6 (∀𝑏 ∈ (Base‘𝐶)∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝑏) → (𝐵 ∈ (Base‘𝐶) → (∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎) → (𝐴 ∈ (Base‘𝐶) → (𝜑 → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))))))
5352com15 101 . . . . 5 (𝜑 → (𝐵 ∈ (Base‘𝐶) → (∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎) → (𝐴 ∈ (Base‘𝐶) → (∀𝑏 ∈ (Base‘𝐶)∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝑏) → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))))))
5453impd 410 . . . 4 (𝜑 → ((𝐵 ∈ (Base‘𝐶) ∧ ∀𝑎 ∈ (Base‘𝐶)∃!𝑔 𝑔 ∈ (𝐵(Hom ‘𝐶)𝑎)) → (𝐴 ∈ (Base‘𝐶) → (∀𝑏 ∈ (Base‘𝐶)∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝑏) → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵)))))
559, 54mpd 15 . . 3 (𝜑 → (𝐴 ∈ (Base‘𝐶) → (∀𝑏 ∈ (Base‘𝐶)∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝑏) → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))))
5655impd 410 . 2 (𝜑 → ((𝐴 ∈ (Base‘𝐶) ∧ ∀𝑏 ∈ (Base‘𝐶)∃!𝑓 𝑓 ∈ (𝐴(Hom ‘𝐶)𝑏)) → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵)))
576, 56mpd 15 1 (𝜑 → ∃!𝑓 𝑓 ∈ (𝐴(Iso‘𝐶)𝐵))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 395   = wceq 1540  wex 1779  wcel 2109  ∃!weu 2561  wral 3044  wss 3905   class class class wbr 5095  cfv 6486  (class class class)co 7353  Basecbs 17138  Hom chom 17190  Catccat 17588  Invcinv 17670  Isociso 17671  InitOcinito 17906
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1910  ax-6 1967  ax-7 2008  ax-8 2111  ax-9 2119  ax-10 2142  ax-11 2158  ax-12 2178  ax-ext 2701  ax-rep 5221  ax-sep 5238  ax-nul 5248  ax-pow 5307  ax-pr 5374  ax-un 7675
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3an 1088  df-tru 1543  df-fal 1553  df-ex 1780  df-nf 1784  df-sb 2066  df-mo 2533  df-eu 2562  df-clab 2708  df-cleq 2721  df-clel 2803  df-nfc 2878  df-ne 2926  df-ral 3045  df-rex 3054  df-rmo 3345  df-reu 3346  df-rab 3397  df-v 3440  df-sbc 3745  df-csb 3854  df-dif 3908  df-un 3910  df-in 3912  df-ss 3922  df-nul 4287  df-if 4479  df-pw 4555  df-sn 4580  df-pr 4582  df-op 4586  df-uni 4862  df-iun 4946  df-br 5096  df-opab 5158  df-mpt 5177  df-id 5518  df-xp 5629  df-rel 5630  df-cnv 5631  df-co 5632  df-dm 5633  df-rn 5634  df-res 5635  df-ima 5636  df-iota 6442  df-fun 6488  df-fn 6489  df-f 6490  df-f1 6491  df-fo 6492  df-f1o 6493  df-fv 6494  df-riota 7310  df-ov 7356  df-oprab 7357  df-mpo 7358  df-1st 7931  df-2nd 7932  df-cat 17592  df-cid 17593  df-sect 17672  df-inv 17673  df-iso 17674  df-inito 17909
This theorem is referenced by:  initoeu1w  17937
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