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Theorem iindif2 4587
 Description: Indexed intersection of class difference. Generalization of half of theorem "De Morgan's laws" in [Enderton] p. 31. Use uniiun 4571 to recover Enderton's theorem. (Contributed by NM, 5-Oct-2006.)
Assertion
Ref Expression
iindif2 (𝐴 ≠ ∅ → 𝑥𝐴 (𝐵𝐶) = (𝐵 𝑥𝐴 𝐶))
Distinct variable groups:   𝑥,𝐴   𝑥,𝐵
Allowed substitution hint:   𝐶(𝑥)

Proof of Theorem iindif2
Dummy variable 𝑦 is distinct from all other variables.
StepHypRef Expression
1 r19.28zv 4064 . . . 4 (𝐴 ≠ ∅ → (∀𝑥𝐴 (𝑦𝐵 ∧ ¬ 𝑦𝐶) ↔ (𝑦𝐵 ∧ ∀𝑥𝐴 ¬ 𝑦𝐶)))
2 eldif 3582 . . . . . 6 (𝑦 ∈ (𝐵𝐶) ↔ (𝑦𝐵 ∧ ¬ 𝑦𝐶))
32bicomi 214 . . . . 5 ((𝑦𝐵 ∧ ¬ 𝑦𝐶) ↔ 𝑦 ∈ (𝐵𝐶))
43ralbii 2979 . . . 4 (∀𝑥𝐴 (𝑦𝐵 ∧ ¬ 𝑦𝐶) ↔ ∀𝑥𝐴 𝑦 ∈ (𝐵𝐶))
5 ralnex 2991 . . . . . 6 (∀𝑥𝐴 ¬ 𝑦𝐶 ↔ ¬ ∃𝑥𝐴 𝑦𝐶)
6 eliun 4522 . . . . . 6 (𝑦 𝑥𝐴 𝐶 ↔ ∃𝑥𝐴 𝑦𝐶)
75, 6xchbinxr 325 . . . . 5 (∀𝑥𝐴 ¬ 𝑦𝐶 ↔ ¬ 𝑦 𝑥𝐴 𝐶)
87anbi2i 730 . . . 4 ((𝑦𝐵 ∧ ∀𝑥𝐴 ¬ 𝑦𝐶) ↔ (𝑦𝐵 ∧ ¬ 𝑦 𝑥𝐴 𝐶))
91, 4, 83bitr3g 302 . . 3 (𝐴 ≠ ∅ → (∀𝑥𝐴 𝑦 ∈ (𝐵𝐶) ↔ (𝑦𝐵 ∧ ¬ 𝑦 𝑥𝐴 𝐶)))
10 vex 3201 . . . 4 𝑦 ∈ V
11 eliin 4523 . . . 4 (𝑦 ∈ V → (𝑦 𝑥𝐴 (𝐵𝐶) ↔ ∀𝑥𝐴 𝑦 ∈ (𝐵𝐶)))
1210, 11ax-mp 5 . . 3 (𝑦 𝑥𝐴 (𝐵𝐶) ↔ ∀𝑥𝐴 𝑦 ∈ (𝐵𝐶))
13 eldif 3582 . . 3 (𝑦 ∈ (𝐵 𝑥𝐴 𝐶) ↔ (𝑦𝐵 ∧ ¬ 𝑦 𝑥𝐴 𝐶))
149, 12, 133bitr4g 303 . 2 (𝐴 ≠ ∅ → (𝑦 𝑥𝐴 (𝐵𝐶) ↔ 𝑦 ∈ (𝐵 𝑥𝐴 𝐶)))
1514eqrdv 2619 1 (𝐴 ≠ ∅ → 𝑥𝐴 (𝐵𝐶) = (𝐵 𝑥𝐴 𝐶))
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 196   ∧ wa 384   = wceq 1482   ∈ wcel 1989   ≠ wne 2793  ∀wral 2911  ∃wrex 2912  Vcvv 3198   ∖ cdif 3569  ∅c0 3913  ∪ ciun 4518  ∩ ciin 4519 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1721  ax-4 1736  ax-5 1838  ax-6 1887  ax-7 1934  ax-9 1998  ax-10 2018  ax-11 2033  ax-12 2046  ax-13 2245  ax-ext 2601 This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-tru 1485  df-ex 1704  df-nf 1709  df-sb 1880  df-clab 2608  df-cleq 2614  df-clel 2617  df-nfc 2752  df-ne 2794  df-ral 2916  df-rex 2917  df-v 3200  df-dif 3575  df-nul 3914  df-iun 4520  df-iin 4521 This theorem is referenced by:  iinvdif  4590  iincld  20837  clsval2  20848  mretopd  20890  hauscmplem  21203  cmpfi  21205  sigapildsyslem  30209  saliincl  40314
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