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Theorem unen 8197
 Description: Equinumerosity of union of disjoint sets. Theorem 4 of [Suppes] p. 92. (Contributed by NM, 11-Jun-1998.) (Revised by Mario Carneiro, 26-Apr-2015.)
Assertion
Ref Expression
unen (((𝐴𝐵𝐶𝐷) ∧ ((𝐴𝐶) = ∅ ∧ (𝐵𝐷) = ∅)) → (𝐴𝐶) ≈ (𝐵𝐷))

Proof of Theorem unen
Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 bren 8122 . . 3 (𝐴𝐵 ↔ ∃𝑥 𝑥:𝐴1-1-onto𝐵)
2 bren 8122 . . 3 (𝐶𝐷 ↔ ∃𝑦 𝑦:𝐶1-1-onto𝐷)
3 eeanv 2319 . . . 4 (∃𝑥𝑦(𝑥:𝐴1-1-onto𝐵𝑦:𝐶1-1-onto𝐷) ↔ (∃𝑥 𝑥:𝐴1-1-onto𝐵 ∧ ∃𝑦 𝑦:𝐶1-1-onto𝐷))
4 vex 3335 . . . . . . . 8 𝑥 ∈ V
5 vex 3335 . . . . . . . 8 𝑦 ∈ V
64, 5unex 7113 . . . . . . 7 (𝑥𝑦) ∈ V
7 f1oun 6309 . . . . . . 7 (((𝑥:𝐴1-1-onto𝐵𝑦:𝐶1-1-onto𝐷) ∧ ((𝐴𝐶) = ∅ ∧ (𝐵𝐷) = ∅)) → (𝑥𝑦):(𝐴𝐶)–1-1-onto→(𝐵𝐷))
8 f1oen3g 8129 . . . . . . 7 (((𝑥𝑦) ∈ V ∧ (𝑥𝑦):(𝐴𝐶)–1-1-onto→(𝐵𝐷)) → (𝐴𝐶) ≈ (𝐵𝐷))
96, 7, 8sylancr 698 . . . . . 6 (((𝑥:𝐴1-1-onto𝐵𝑦:𝐶1-1-onto𝐷) ∧ ((𝐴𝐶) = ∅ ∧ (𝐵𝐷) = ∅)) → (𝐴𝐶) ≈ (𝐵𝐷))
109ex 449 . . . . 5 ((𝑥:𝐴1-1-onto𝐵𝑦:𝐶1-1-onto𝐷) → (((𝐴𝐶) = ∅ ∧ (𝐵𝐷) = ∅) → (𝐴𝐶) ≈ (𝐵𝐷)))
1110exlimivv 2001 . . . 4 (∃𝑥𝑦(𝑥:𝐴1-1-onto𝐵𝑦:𝐶1-1-onto𝐷) → (((𝐴𝐶) = ∅ ∧ (𝐵𝐷) = ∅) → (𝐴𝐶) ≈ (𝐵𝐷)))
123, 11sylbir 225 . . 3 ((∃𝑥 𝑥:𝐴1-1-onto𝐵 ∧ ∃𝑦 𝑦:𝐶1-1-onto𝐷) → (((𝐴𝐶) = ∅ ∧ (𝐵𝐷) = ∅) → (𝐴𝐶) ≈ (𝐵𝐷)))
131, 2, 12syl2anb 497 . 2 ((𝐴𝐵𝐶𝐷) → (((𝐴𝐶) = ∅ ∧ (𝐵𝐷) = ∅) → (𝐴𝐶) ≈ (𝐵𝐷)))
1413imp 444 1 (((𝐴𝐵𝐶𝐷) ∧ ((𝐴𝐶) = ∅ ∧ (𝐵𝐷) = ∅)) → (𝐴𝐶) ≈ (𝐵𝐷))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ∧ wa 383   = wceq 1624  ∃wex 1845   ∈ wcel 2131  Vcvv 3332   ∪ cun 3705   ∩ cin 3706  ∅c0 4050   class class class wbr 4796  –1-1-onto→wf1o 6040   ≈ cen 8110 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1863  ax-4 1878  ax-5 1980  ax-6 2046  ax-7 2082  ax-8 2133  ax-9 2140  ax-10 2160  ax-11 2175  ax-12 2188  ax-13 2383  ax-ext 2732  ax-sep 4925  ax-nul 4933  ax-pr 5047  ax-un 7106 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-3an 1074  df-tru 1627  df-ex 1846  df-nf 1851  df-sb 2039  df-eu 2603  df-mo 2604  df-clab 2739  df-cleq 2745  df-clel 2748  df-nfc 2883  df-ral 3047  df-rex 3048  df-rab 3051  df-v 3334  df-dif 3710  df-un 3712  df-in 3714  df-ss 3721  df-nul 4051  df-if 4223  df-sn 4314  df-pr 4316  df-op 4320  df-uni 4581  df-br 4797  df-opab 4857  df-id 5166  df-xp 5264  df-rel 5265  df-cnv 5266  df-co 5267  df-dm 5268  df-rn 5269  df-fun 6043  df-fn 6044  df-f 6045  df-f1 6046  df-fo 6047  df-f1o 6048  df-en 8114 This theorem is referenced by:  difsnen  8199  undom  8205  limensuci  8293  infensuc  8295  phplem2  8297  pssnn  8335  dif1en  8350  unfi  8384  infdifsn  8719  pm54.43  9008  dif1card  9015  cdaun  9178  cdaen  9179  ssfin4  9316  fin23lem26  9331  unsnen  9559  fzennn  12953  mreexexlem4d  16501
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