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Theorem un4 3908
 Description: A rearrangement of the union of 4 classes. (Contributed by NM, 12-Aug-2004.)
Assertion
Ref Expression
un4 ((𝐴𝐵) ∪ (𝐶𝐷)) = ((𝐴𝐶) ∪ (𝐵𝐷))

Proof of Theorem un4
StepHypRef Expression
1 un12 3906 . . 3 (𝐵 ∪ (𝐶𝐷)) = (𝐶 ∪ (𝐵𝐷))
21uneq2i 3899 . 2 (𝐴 ∪ (𝐵 ∪ (𝐶𝐷))) = (𝐴 ∪ (𝐶 ∪ (𝐵𝐷)))
3 unass 3905 . 2 ((𝐴𝐵) ∪ (𝐶𝐷)) = (𝐴 ∪ (𝐵 ∪ (𝐶𝐷)))
4 unass 3905 . 2 ((𝐴𝐶) ∪ (𝐵𝐷)) = (𝐴 ∪ (𝐶 ∪ (𝐵𝐷)))
52, 3, 43eqtr4i 2784 1 ((𝐴𝐵) ∪ (𝐶𝐷)) = ((𝐴𝐶) ∪ (𝐵𝐷))
 Colors of variables: wff setvar class Syntax hints:   = wceq 1624   ∪ cun 3705 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-9 2140  ax-10 2160  ax-11 2175  ax-12 2188  ax-13 2383  ax-ext 2732 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-tru 1627  df-ex 1846  df-nf 1851  df-sb 2039  df-clab 2739  df-cleq 2745  df-clel 2748  df-nfc 2883  df-v 3334  df-un 3712 This theorem is referenced by:  unundi  3909  unundir  3910  xpun  5325  resasplit  6227  ex-pw  27589  iunrelexp0  38488
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