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Theorem djur 9414
Description: A member of a disjoint union can be mapped from one of the classes which produced it. (Contributed by Jim Kingdon, 23-Jun-2022.)
Assertion
Ref Expression
djur (𝐶 ∈ (𝐴𝐵) → (∃𝑥𝐴 𝐶 = (inl‘𝑥) ∨ ∃𝑥𝐵 𝐶 = (inr‘𝑥)))
Distinct variable groups:   𝑥,𝐴   𝑥,𝐵   𝑥,𝐶

Proof of Theorem djur
Dummy variables 𝑦 𝑧 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 df-dju 9396 . . . 4 (𝐴𝐵) = (({∅} × 𝐴) ∪ ({1o} × 𝐵))
21eleq2i 2824 . . 3 (𝐶 ∈ (𝐴𝐵) ↔ 𝐶 ∈ (({∅} × 𝐴) ∪ ({1o} × 𝐵)))
3 elun 4037 . . 3 (𝐶 ∈ (({∅} × 𝐴) ∪ ({1o} × 𝐵)) ↔ (𝐶 ∈ ({∅} × 𝐴) ∨ 𝐶 ∈ ({1o} × 𝐵)))
42, 3sylbb 222 . 2 (𝐶 ∈ (𝐴𝐵) → (𝐶 ∈ ({∅} × 𝐴) ∨ 𝐶 ∈ ({1o} × 𝐵)))
5 xp2nd 7740 . . . 4 (𝐶 ∈ ({∅} × 𝐴) → (2nd𝐶) ∈ 𝐴)
6 1st2nd2 7746 . . . . . 6 (𝐶 ∈ ({∅} × 𝐴) → 𝐶 = ⟨(1st𝐶), (2nd𝐶)⟩)
7 xp1st 7739 . . . . . . 7 (𝐶 ∈ ({∅} × 𝐴) → (1st𝐶) ∈ {∅})
8 elsni 4530 . . . . . . 7 ((1st𝐶) ∈ {∅} → (1st𝐶) = ∅)
9 opeq1 4756 . . . . . . . 8 ((1st𝐶) = ∅ → ⟨(1st𝐶), (2nd𝐶)⟩ = ⟨∅, (2nd𝐶)⟩)
109eqeq2d 2749 . . . . . . 7 ((1st𝐶) = ∅ → (𝐶 = ⟨(1st𝐶), (2nd𝐶)⟩ ↔ 𝐶 = ⟨∅, (2nd𝐶)⟩))
117, 8, 103syl 18 . . . . . 6 (𝐶 ∈ ({∅} × 𝐴) → (𝐶 = ⟨(1st𝐶), (2nd𝐶)⟩ ↔ 𝐶 = ⟨∅, (2nd𝐶)⟩))
126, 11mpbid 235 . . . . 5 (𝐶 ∈ ({∅} × 𝐴) → 𝐶 = ⟨∅, (2nd𝐶)⟩)
13 fvexd 6683 . . . . . 6 (𝐶 ∈ ({∅} × 𝐴) → (2nd𝐶) ∈ V)
14 opex 5319 . . . . . 6 ⟨∅, (2nd𝐶)⟩ ∈ V
15 opeq2 4758 . . . . . . 7 (𝑦 = (2nd𝐶) → ⟨∅, 𝑦⟩ = ⟨∅, (2nd𝐶)⟩)
16 df-inl 9397 . . . . . . 7 inl = (𝑦 ∈ V ↦ ⟨∅, 𝑦⟩)
1715, 16fvmptg 6767 . . . . . 6 (((2nd𝐶) ∈ V ∧ ⟨∅, (2nd𝐶)⟩ ∈ V) → (inl‘(2nd𝐶)) = ⟨∅, (2nd𝐶)⟩)
1813, 14, 17sylancl 589 . . . . 5 (𝐶 ∈ ({∅} × 𝐴) → (inl‘(2nd𝐶)) = ⟨∅, (2nd𝐶)⟩)
1912, 18eqtr4d 2776 . . . 4 (𝐶 ∈ ({∅} × 𝐴) → 𝐶 = (inl‘(2nd𝐶)))
20 fveq2 6668 . . . . 5 (𝑥 = (2nd𝐶) → (inl‘𝑥) = (inl‘(2nd𝐶)))
2120rspceeqv 3539 . . . 4 (((2nd𝐶) ∈ 𝐴𝐶 = (inl‘(2nd𝐶))) → ∃𝑥𝐴 𝐶 = (inl‘𝑥))
225, 19, 21syl2anc 587 . . 3 (𝐶 ∈ ({∅} × 𝐴) → ∃𝑥𝐴 𝐶 = (inl‘𝑥))
23 xp2nd 7740 . . . 4 (𝐶 ∈ ({1o} × 𝐵) → (2nd𝐶) ∈ 𝐵)
24 1st2nd2 7746 . . . . . 6 (𝐶 ∈ ({1o} × 𝐵) → 𝐶 = ⟨(1st𝐶), (2nd𝐶)⟩)
25 xp1st 7739 . . . . . . 7 (𝐶 ∈ ({1o} × 𝐵) → (1st𝐶) ∈ {1o})
26 elsni 4530 . . . . . . 7 ((1st𝐶) ∈ {1o} → (1st𝐶) = 1o)
27 opeq1 4756 . . . . . . . 8 ((1st𝐶) = 1o → ⟨(1st𝐶), (2nd𝐶)⟩ = ⟨1o, (2nd𝐶)⟩)
2827eqeq2d 2749 . . . . . . 7 ((1st𝐶) = 1o → (𝐶 = ⟨(1st𝐶), (2nd𝐶)⟩ ↔ 𝐶 = ⟨1o, (2nd𝐶)⟩))
2925, 26, 283syl 18 . . . . . 6 (𝐶 ∈ ({1o} × 𝐵) → (𝐶 = ⟨(1st𝐶), (2nd𝐶)⟩ ↔ 𝐶 = ⟨1o, (2nd𝐶)⟩))
3024, 29mpbid 235 . . . . 5 (𝐶 ∈ ({1o} × 𝐵) → 𝐶 = ⟨1o, (2nd𝐶)⟩)
31 fvexd 6683 . . . . . 6 (𝐶 ∈ ({1o} × 𝐵) → (2nd𝐶) ∈ V)
32 opex 5319 . . . . . 6 ⟨1o, (2nd𝐶)⟩ ∈ V
33 opeq2 4758 . . . . . . 7 (𝑧 = (2nd𝐶) → ⟨1o, 𝑧⟩ = ⟨1o, (2nd𝐶)⟩)
34 df-inr 9398 . . . . . . 7 inr = (𝑧 ∈ V ↦ ⟨1o, 𝑧⟩)
3533, 34fvmptg 6767 . . . . . 6 (((2nd𝐶) ∈ V ∧ ⟨1o, (2nd𝐶)⟩ ∈ V) → (inr‘(2nd𝐶)) = ⟨1o, (2nd𝐶)⟩)
3631, 32, 35sylancl 589 . . . . 5 (𝐶 ∈ ({1o} × 𝐵) → (inr‘(2nd𝐶)) = ⟨1o, (2nd𝐶)⟩)
3730, 36eqtr4d 2776 . . . 4 (𝐶 ∈ ({1o} × 𝐵) → 𝐶 = (inr‘(2nd𝐶)))
38 fveq2 6668 . . . . 5 (𝑥 = (2nd𝐶) → (inr‘𝑥) = (inr‘(2nd𝐶)))
3938rspceeqv 3539 . . . 4 (((2nd𝐶) ∈ 𝐵𝐶 = (inr‘(2nd𝐶))) → ∃𝑥𝐵 𝐶 = (inr‘𝑥))
4023, 37, 39syl2anc 587 . . 3 (𝐶 ∈ ({1o} × 𝐵) → ∃𝑥𝐵 𝐶 = (inr‘𝑥))
4122, 40orim12i 908 . 2 ((𝐶 ∈ ({∅} × 𝐴) ∨ 𝐶 ∈ ({1o} × 𝐵)) → (∃𝑥𝐴 𝐶 = (inl‘𝑥) ∨ ∃𝑥𝐵 𝐶 = (inr‘𝑥)))
424, 41syl 17 1 (𝐶 ∈ (𝐴𝐵) → (∃𝑥𝐴 𝐶 = (inl‘𝑥) ∨ ∃𝑥𝐵 𝐶 = (inr‘𝑥)))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 209  wo 846   = wceq 1542  wcel 2113  wrex 3054  Vcvv 3397  cun 3839  c0 4209  {csn 4513  cop 4519   × cxp 5517  cfv 6333  1st c1st 7705  2nd c2nd 7706  1oc1o 8117  cdju 9393  inlcinl 9394  inrcinr 9395
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1802  ax-4 1816  ax-5 1916  ax-6 1974  ax-7 2019  ax-8 2115  ax-9 2123  ax-10 2144  ax-11 2161  ax-12 2178  ax-ext 2710  ax-sep 5164  ax-nul 5171  ax-pr 5293  ax-un 7473
This theorem depends on definitions:  df-bi 210  df-an 400  df-or 847  df-3an 1090  df-tru 1545  df-fal 1555  df-ex 1787  df-nf 1791  df-sb 2074  df-mo 2540  df-eu 2570  df-clab 2717  df-cleq 2730  df-clel 2811  df-nfc 2881  df-ne 2935  df-ral 3058  df-rex 3059  df-rab 3062  df-v 3399  df-sbc 3680  df-dif 3844  df-un 3846  df-in 3848  df-ss 3858  df-nul 4210  df-if 4412  df-sn 4514  df-pr 4516  df-op 4520  df-uni 4794  df-br 5028  df-opab 5090  df-mpt 5108  df-id 5425  df-xp 5525  df-rel 5526  df-cnv 5527  df-co 5528  df-dm 5529  df-rn 5530  df-iota 6291  df-fun 6335  df-fv 6341  df-1st 7707  df-2nd 7708  df-dju 9396  df-inl 9397  df-inr 9398
This theorem is referenced by:  djuss  9415  djuun  9421  updjud  9429
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