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Theorem ecelqsg 6247
 Description: Membership of an equivalence class in a quotient set. (Contributed by Jeff Madsen, 10-Jun-2010.) (Revised by Mario Carneiro, 9-Jul-2014.)
Assertion
Ref Expression
ecelqsg ((𝑅𝑉𝐵𝐴) → [𝐵]𝑅 ∈ (𝐴 / 𝑅))

Proof of Theorem ecelqsg
Dummy variable 𝑥 is distinct from all other variables.
StepHypRef Expression
1 eqid 2083 . . 3 [𝐵]𝑅 = [𝐵]𝑅
2 eceq1 6229 . . . . 5 (𝑥 = 𝐵 → [𝑥]𝑅 = [𝐵]𝑅)
32eqeq2d 2094 . . . 4 (𝑥 = 𝐵 → ([𝐵]𝑅 = [𝑥]𝑅 ↔ [𝐵]𝑅 = [𝐵]𝑅))
43rspcev 2710 . . 3 ((𝐵𝐴 ∧ [𝐵]𝑅 = [𝐵]𝑅) → ∃𝑥𝐴 [𝐵]𝑅 = [𝑥]𝑅)
51, 4mpan2 416 . 2 (𝐵𝐴 → ∃𝑥𝐴 [𝐵]𝑅 = [𝑥]𝑅)
6 ecexg 6198 . . . 4 (𝑅𝑉 → [𝐵]𝑅 ∈ V)
7 elqsg 6244 . . . 4 ([𝐵]𝑅 ∈ V → ([𝐵]𝑅 ∈ (𝐴 / 𝑅) ↔ ∃𝑥𝐴 [𝐵]𝑅 = [𝑥]𝑅))
86, 7syl 14 . . 3 (𝑅𝑉 → ([𝐵]𝑅 ∈ (𝐴 / 𝑅) ↔ ∃𝑥𝐴 [𝐵]𝑅 = [𝑥]𝑅))
98biimpar 291 . 2 ((𝑅𝑉 ∧ ∃𝑥𝐴 [𝐵]𝑅 = [𝑥]𝑅) → [𝐵]𝑅 ∈ (𝐴 / 𝑅))
105, 9sylan2 280 1 ((𝑅𝑉𝐵𝐴) → [𝐵]𝑅 ∈ (𝐴 / 𝑅))
 Colors of variables: wff set class Syntax hints:   → wi 4   ∧ wa 102   ↔ wb 103   = wceq 1285   ∈ wcel 1434  ∃wrex 2354  Vcvv 2610  [cec 6192   / cqs 6193 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 663  ax-5 1377  ax-7 1378  ax-gen 1379  ax-ie1 1423  ax-ie2 1424  ax-8 1436  ax-10 1437  ax-11 1438  ax-i12 1439  ax-bndl 1440  ax-4 1441  ax-13 1445  ax-14 1446  ax-17 1460  ax-i9 1464  ax-ial 1468  ax-i5r 1469  ax-ext 2065  ax-sep 3916  ax-pow 3968  ax-pr 3992  ax-un 4216 This theorem depends on definitions:  df-bi 115  df-3an 922  df-tru 1288  df-nf 1391  df-sb 1688  df-eu 1946  df-mo 1947  df-clab 2070  df-cleq 2076  df-clel 2079  df-nfc 2212  df-ral 2358  df-rex 2359  df-v 2612  df-un 2986  df-in 2988  df-ss 2995  df-pw 3402  df-sn 3422  df-pr 3423  df-op 3425  df-uni 3622  df-br 3806  df-opab 3860  df-xp 4397  df-cnv 4399  df-dm 4401  df-rn 4402  df-res 4403  df-ima 4404  df-ec 6196  df-qs 6200 This theorem is referenced by:  ecelqsi  6248  qliftlem  6272  eroprf  6287
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