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Theorem coundi 5795
 Description: Class composition distributes over union. (Contributed by NM, 21-Dec-2008.) (Proof shortened by Andrew Salmon, 27-Aug-2011.)
Assertion
Ref Expression
coundi (𝐴 ∘ (𝐵𝐶)) = ((𝐴𝐵) ∪ (𝐴𝐶))

Proof of Theorem coundi
Dummy variables 𝑥 𝑦 𝑧 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 unopab 4878 . . 3 ({⟨𝑥, 𝑦⟩ ∣ ∃𝑧(𝑥𝐵𝑧𝑧𝐴𝑦)} ∪ {⟨𝑥, 𝑦⟩ ∣ ∃𝑧(𝑥𝐶𝑧𝑧𝐴𝑦)}) = {⟨𝑥, 𝑦⟩ ∣ (∃𝑧(𝑥𝐵𝑧𝑧𝐴𝑦) ∨ ∃𝑧(𝑥𝐶𝑧𝑧𝐴𝑦))}
2 brun 4853 . . . . . . . 8 (𝑥(𝐵𝐶)𝑧 ↔ (𝑥𝐵𝑧𝑥𝐶𝑧))
32anbi1i 733 . . . . . . 7 ((𝑥(𝐵𝐶)𝑧𝑧𝐴𝑦) ↔ ((𝑥𝐵𝑧𝑥𝐶𝑧) ∧ 𝑧𝐴𝑦))
4 andir 948 . . . . . . 7 (((𝑥𝐵𝑧𝑥𝐶𝑧) ∧ 𝑧𝐴𝑦) ↔ ((𝑥𝐵𝑧𝑧𝐴𝑦) ∨ (𝑥𝐶𝑧𝑧𝐴𝑦)))
53, 4bitri 264 . . . . . 6 ((𝑥(𝐵𝐶)𝑧𝑧𝐴𝑦) ↔ ((𝑥𝐵𝑧𝑧𝐴𝑦) ∨ (𝑥𝐶𝑧𝑧𝐴𝑦)))
65exbii 1921 . . . . 5 (∃𝑧(𝑥(𝐵𝐶)𝑧𝑧𝐴𝑦) ↔ ∃𝑧((𝑥𝐵𝑧𝑧𝐴𝑦) ∨ (𝑥𝐶𝑧𝑧𝐴𝑦)))
7 19.43 1957 . . . . 5 (∃𝑧((𝑥𝐵𝑧𝑧𝐴𝑦) ∨ (𝑥𝐶𝑧𝑧𝐴𝑦)) ↔ (∃𝑧(𝑥𝐵𝑧𝑧𝐴𝑦) ∨ ∃𝑧(𝑥𝐶𝑧𝑧𝐴𝑦)))
86, 7bitr2i 265 . . . 4 ((∃𝑧(𝑥𝐵𝑧𝑧𝐴𝑦) ∨ ∃𝑧(𝑥𝐶𝑧𝑧𝐴𝑦)) ↔ ∃𝑧(𝑥(𝐵𝐶)𝑧𝑧𝐴𝑦))
98opabbii 4867 . . 3 {⟨𝑥, 𝑦⟩ ∣ (∃𝑧(𝑥𝐵𝑧𝑧𝐴𝑦) ∨ ∃𝑧(𝑥𝐶𝑧𝑧𝐴𝑦))} = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧(𝑥(𝐵𝐶)𝑧𝑧𝐴𝑦)}
101, 9eqtri 2780 . 2 ({⟨𝑥, 𝑦⟩ ∣ ∃𝑧(𝑥𝐵𝑧𝑧𝐴𝑦)} ∪ {⟨𝑥, 𝑦⟩ ∣ ∃𝑧(𝑥𝐶𝑧𝑧𝐴𝑦)}) = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧(𝑥(𝐵𝐶)𝑧𝑧𝐴𝑦)}
11 df-co 5273 . . 3 (𝐴𝐵) = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧(𝑥𝐵𝑧𝑧𝐴𝑦)}
12 df-co 5273 . . 3 (𝐴𝐶) = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧(𝑥𝐶𝑧𝑧𝐴𝑦)}
1311, 12uneq12i 3906 . 2 ((𝐴𝐵) ∪ (𝐴𝐶)) = ({⟨𝑥, 𝑦⟩ ∣ ∃𝑧(𝑥𝐵𝑧𝑧𝐴𝑦)} ∪ {⟨𝑥, 𝑦⟩ ∣ ∃𝑧(𝑥𝐶𝑧𝑧𝐴𝑦)})
14 df-co 5273 . 2 (𝐴 ∘ (𝐵𝐶)) = {⟨𝑥, 𝑦⟩ ∣ ∃𝑧(𝑥(𝐵𝐶)𝑧𝑧𝐴𝑦)}
1510, 13, 143eqtr4ri 2791 1 (𝐴 ∘ (𝐵𝐶)) = ((𝐴𝐵) ∪ (𝐴𝐶))
 Colors of variables: wff setvar class Syntax hints:   ∨ wo 382   ∧ wa 383   = wceq 1630  ∃wex 1851   ∪ cun 3711   class class class wbr 4802  {copab 4862   ∘ ccom 5268 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1869  ax-4 1884  ax-5 1986  ax-6 2052  ax-7 2088  ax-9 2146  ax-10 2166  ax-11 2181  ax-12 2194  ax-13 2389  ax-ext 2738 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-tru 1633  df-ex 1852  df-nf 1857  df-sb 2045  df-clab 2745  df-cleq 2751  df-clel 2754  df-nfc 2889  df-v 3340  df-un 3718  df-br 4803  df-opab 4863  df-co 5273 This theorem is referenced by:  mvdco  18063  ustssco  22217  cvmliftlem10  31581  poimirlem9  33729  diophren  37877  rtrclex  38424  trclubgNEW  38425  trclexi  38427  rtrclexi  38428  cnvtrcl0  38433  trrelsuperrel2dg  38463  cotrclrcl  38534  frege131d  38556
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