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Theorem xpundi 4421
 Description: Distributive law for cross product over union. Theorem 103 of [Suppes] p. 52. (Contributed by NM, 12-Aug-2004.)
Assertion
Ref Expression
xpundi (𝐴 × (𝐵𝐶)) = ((𝐴 × 𝐵) ∪ (𝐴 × 𝐶))

Proof of Theorem xpundi
Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 df-xp 4376 . 2 (𝐴 × (𝐵𝐶)) = {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦 ∈ (𝐵𝐶))}
2 df-xp 4376 . . . 4 (𝐴 × 𝐵) = {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝐵)}
3 df-xp 4376 . . . 4 (𝐴 × 𝐶) = {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝐶)}
42, 3uneq12i 3120 . . 3 ((𝐴 × 𝐵) ∪ (𝐴 × 𝐶)) = ({⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝐵)} ∪ {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝐶)})
5 elun 3109 . . . . . . 7 (𝑦 ∈ (𝐵𝐶) ↔ (𝑦𝐵𝑦𝐶))
65anbi2i 438 . . . . . 6 ((𝑥𝐴𝑦 ∈ (𝐵𝐶)) ↔ (𝑥𝐴 ∧ (𝑦𝐵𝑦𝐶)))
7 andi 740 . . . . . 6 ((𝑥𝐴 ∧ (𝑦𝐵𝑦𝐶)) ↔ ((𝑥𝐴𝑦𝐵) ∨ (𝑥𝐴𝑦𝐶)))
86, 7bitri 177 . . . . 5 ((𝑥𝐴𝑦 ∈ (𝐵𝐶)) ↔ ((𝑥𝐴𝑦𝐵) ∨ (𝑥𝐴𝑦𝐶)))
98opabbii 3849 . . . 4 {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦 ∈ (𝐵𝐶))} = {⟨𝑥, 𝑦⟩ ∣ ((𝑥𝐴𝑦𝐵) ∨ (𝑥𝐴𝑦𝐶))}
10 unopab 3861 . . . 4 ({⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝐵)} ∪ {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝐶)}) = {⟨𝑥, 𝑦⟩ ∣ ((𝑥𝐴𝑦𝐵) ∨ (𝑥𝐴𝑦𝐶))}
119, 10eqtr4i 2077 . . 3 {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦 ∈ (𝐵𝐶))} = ({⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝐵)} ∪ {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝐶)})
124, 11eqtr4i 2077 . 2 ((𝐴 × 𝐵) ∪ (𝐴 × 𝐶)) = {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦 ∈ (𝐵𝐶))}
131, 12eqtr4i 2077 1 (𝐴 × (𝐵𝐶)) = ((𝐴 × 𝐵) ∪ (𝐴 × 𝐶))
 Colors of variables: wff set class Syntax hints:   ∧ wa 101   ∨ wo 637   = wceq 1257   ∈ wcel 1407   ∪ cun 2940  {copab 3842   × cxp 4368 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-io 638  ax-5 1350  ax-7 1351  ax-gen 1352  ax-ie1 1396  ax-ie2 1397  ax-8 1409  ax-10 1410  ax-11 1411  ax-i12 1412  ax-bndl 1413  ax-4 1414  ax-17 1433  ax-i9 1437  ax-ial 1441  ax-i5r 1442  ax-ext 2036 This theorem depends on definitions:  df-bi 114  df-tru 1260  df-nf 1364  df-sb 1660  df-clab 2041  df-cleq 2047  df-clel 2050  df-nfc 2181  df-v 2574  df-un 2947  df-opab 3844  df-xp 4376 This theorem is referenced by:  xpun  4426
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