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Theorem uniiunlem 3244
Description: A subset relationship useful for converting union to indexed union using dfiun2 or dfiun2g and intersection to indexed intersection using dfiin2 . (Contributed by NM, 5-Oct-2006.) (Proof shortened by Mario Carneiro, 26-Sep-2015.)
Assertion
Ref Expression
uniiunlem (∀𝑥𝐴 𝐵𝐷 → (∀𝑥𝐴 𝐵𝐶 ↔ {𝑦 ∣ ∃𝑥𝐴 𝑦 = 𝐵} ⊆ 𝐶))
Distinct variable groups:   𝑥,𝑦   𝑦,𝐴   𝑦,𝐵   𝑥,𝐶
Allowed substitution hints:   𝐴(𝑥)   𝐵(𝑥)   𝐶(𝑦)   𝐷(𝑥,𝑦)

Proof of Theorem uniiunlem
Dummy variable 𝑧 is distinct from all other variables.
StepHypRef Expression
1 eqeq1 2184 . . . . . 6 (𝑦 = 𝑧 → (𝑦 = 𝐵𝑧 = 𝐵))
21rexbidv 2478 . . . . 5 (𝑦 = 𝑧 → (∃𝑥𝐴 𝑦 = 𝐵 ↔ ∃𝑥𝐴 𝑧 = 𝐵))
32cbvabv 2302 . . . 4 {𝑦 ∣ ∃𝑥𝐴 𝑦 = 𝐵} = {𝑧 ∣ ∃𝑥𝐴 𝑧 = 𝐵}
43sseq1i 3181 . . 3 ({𝑦 ∣ ∃𝑥𝐴 𝑦 = 𝐵} ⊆ 𝐶 ↔ {𝑧 ∣ ∃𝑥𝐴 𝑧 = 𝐵} ⊆ 𝐶)
5 r19.23v 2586 . . . . 5 (∀𝑥𝐴 (𝑧 = 𝐵𝑧𝐶) ↔ (∃𝑥𝐴 𝑧 = 𝐵𝑧𝐶))
65albii 1470 . . . 4 (∀𝑧𝑥𝐴 (𝑧 = 𝐵𝑧𝐶) ↔ ∀𝑧(∃𝑥𝐴 𝑧 = 𝐵𝑧𝐶))
7 ralcom4 2759 . . . 4 (∀𝑥𝐴𝑧(𝑧 = 𝐵𝑧𝐶) ↔ ∀𝑧𝑥𝐴 (𝑧 = 𝐵𝑧𝐶))
8 abss 3224 . . . 4 ({𝑧 ∣ ∃𝑥𝐴 𝑧 = 𝐵} ⊆ 𝐶 ↔ ∀𝑧(∃𝑥𝐴 𝑧 = 𝐵𝑧𝐶))
96, 7, 83bitr4i 212 . . 3 (∀𝑥𝐴𝑧(𝑧 = 𝐵𝑧𝐶) ↔ {𝑧 ∣ ∃𝑥𝐴 𝑧 = 𝐵} ⊆ 𝐶)
104, 9bitr4i 187 . 2 ({𝑦 ∣ ∃𝑥𝐴 𝑦 = 𝐵} ⊆ 𝐶 ↔ ∀𝑥𝐴𝑧(𝑧 = 𝐵𝑧𝐶))
11 nfv 1528 . . . . 5 𝑧 𝐵𝐶
12 eleq1 2240 . . . . 5 (𝑧 = 𝐵 → (𝑧𝐶𝐵𝐶))
1311, 12ceqsalg 2765 . . . 4 (𝐵𝐷 → (∀𝑧(𝑧 = 𝐵𝑧𝐶) ↔ 𝐵𝐶))
1413ralimi 2540 . . 3 (∀𝑥𝐴 𝐵𝐷 → ∀𝑥𝐴 (∀𝑧(𝑧 = 𝐵𝑧𝐶) ↔ 𝐵𝐶))
15 ralbi 2609 . . 3 (∀𝑥𝐴 (∀𝑧(𝑧 = 𝐵𝑧𝐶) ↔ 𝐵𝐶) → (∀𝑥𝐴𝑧(𝑧 = 𝐵𝑧𝐶) ↔ ∀𝑥𝐴 𝐵𝐶))
1614, 15syl 14 . 2 (∀𝑥𝐴 𝐵𝐷 → (∀𝑥𝐴𝑧(𝑧 = 𝐵𝑧𝐶) ↔ ∀𝑥𝐴 𝐵𝐶))
1710, 16bitr2id 193 1 (∀𝑥𝐴 𝐵𝐷 → (∀𝑥𝐴 𝐵𝐶 ↔ {𝑦 ∣ ∃𝑥𝐴 𝑦 = 𝐵} ⊆ 𝐶))
Colors of variables: wff set class
Syntax hints:  wi 4  wb 105  wal 1351   = wceq 1353  wcel 2148  {cab 2163  wral 2455  wrex 2456  wss 3129
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 709  ax-5 1447  ax-7 1448  ax-gen 1449  ax-ie1 1493  ax-ie2 1494  ax-8 1504  ax-10 1505  ax-11 1506  ax-i12 1507  ax-bndl 1509  ax-4 1510  ax-17 1526  ax-i9 1530  ax-ial 1534  ax-i5r 1535  ax-ext 2159
This theorem depends on definitions:  df-bi 117  df-tru 1356  df-nf 1461  df-sb 1763  df-clab 2164  df-cleq 2170  df-clel 2173  df-nfc 2308  df-ral 2460  df-rex 2461  df-v 2739  df-in 3135  df-ss 3142
This theorem is referenced by:  iunopn  13393
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