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Theorem dfac8c 8739
 Description: If the union of a set is well-orderable, then the set has a choice function. (Contributed by Mario Carneiro, 5-Jan-2013.)
Assertion
Ref Expression
dfac8c (𝐴𝐵 → (∃𝑟 𝑟 We 𝐴 → ∃𝑓𝑧𝐴 (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧)))
Distinct variable groups:   𝑓,𝑟,𝑧,𝐴   𝐵,𝑟
Allowed substitution hints:   𝐵(𝑧,𝑓)

Proof of Theorem dfac8c
Dummy variables 𝑤 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 eqid 2610 . 2 (𝑥 ∈ (𝐴 ∖ {∅}) ↦ (𝑦𝑥𝑤𝑥 ¬ 𝑤𝑟𝑦)) = (𝑥 ∈ (𝐴 ∖ {∅}) ↦ (𝑦𝑥𝑤𝑥 ¬ 𝑤𝑟𝑦))
21dfac8clem 8738 1 (𝐴𝐵 → (∃𝑟 𝑟 We 𝐴 → ∃𝑓𝑧𝐴 (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧)))
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4  ∃wex 1695   ∈ wcel 1977   ≠ wne 2780  ∀wral 2896   ∖ cdif 3537  ∅c0 3874  {csn 4125  ∪ cuni 4372   class class class wbr 4583   ↦ cmpt 4643   We wwe 4996  ‘cfv 5804  ℩crio 6510 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-8 1979  ax-9 1986  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590  ax-sep 4709  ax-nul 4717  ax-pow 4769  ax-pr 4833  ax-un 6847 This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-3or 1032  df-3an 1033  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-eu 2462  df-mo 2463  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-ne 2782  df-ral 2901  df-rex 2902  df-reu 2903  df-rmo 2904  df-rab 2905  df-v 3175  df-sbc 3403  df-csb 3500  df-dif 3543  df-un 3545  df-in 3547  df-ss 3554  df-nul 3875  df-if 4037  df-pw 4110  df-sn 4126  df-pr 4128  df-op 4132  df-uni 4373  df-br 4584  df-opab 4644  df-mpt 4645  df-id 4953  df-po 4959  df-so 4960  df-fr 4997  df-se 4998  df-we 4999  df-xp 5044  df-rel 5045  df-cnv 5046  df-co 5047  df-dm 5048  df-rn 5049  df-res 5050  df-ima 5051  df-iota 5768  df-fun 5806  df-fn 5807  df-f 5808  df-fv 5812  df-riota 6511 This theorem is referenced by:  ween  8741  ac5num  8742  dfac8  8840  vitali  23188
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