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Theorem n0el2 38315
Description: Two ways of expressing that the empty set is not an element of a class. (Contributed by Peter Mazsa, 31-Jan-2018.)
Assertion
Ref Expression
n0el2 (¬ ∅ ∈ 𝐴 ↔ dom ( E ↾ 𝐴) = 𝐴)

Proof of Theorem n0el2
Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 dmopab3 5933 . 2 (∀𝑥𝐴𝑦 𝑦𝑥 ↔ dom {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝑥)} = 𝐴)
2 n0el 4370 . 2 (¬ ∅ ∈ 𝐴 ↔ ∀𝑥𝐴𝑦 𝑦𝑥)
3 cnvepres 38280 . . . 4 ( E ↾ 𝐴) = {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝑥)}
43dmeqi 5918 . . 3 dom ( E ↾ 𝐴) = dom {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝑥)}
54eqeq1i 2740 . 2 (dom ( E ↾ 𝐴) = 𝐴 ↔ dom {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝑥)} = 𝐴)
61, 2, 53bitr4i 303 1 (¬ ∅ ∈ 𝐴 ↔ dom ( E ↾ 𝐴) = 𝐴)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wb 206  wa 395   = wceq 1537  wex 1776  wcel 2106  wral 3059  c0 4339  {copab 5210   E cep 5588  ccnv 5688  dom cdm 5689  cres 5691
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1792  ax-4 1806  ax-5 1908  ax-6 1965  ax-7 2005  ax-8 2108  ax-9 2116  ax-10 2139  ax-11 2155  ax-12 2175  ax-ext 2706  ax-sep 5302  ax-nul 5312  ax-pr 5438
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3an 1088  df-tru 1540  df-fal 1550  df-ex 1777  df-nf 1781  df-sb 2063  df-mo 2538  df-eu 2567  df-clab 2713  df-cleq 2727  df-clel 2814  df-nfc 2890  df-ne 2939  df-ral 3060  df-rex 3069  df-rab 3434  df-v 3480  df-dif 3966  df-un 3968  df-in 3970  df-ss 3980  df-nul 4340  df-if 4532  df-sn 4632  df-pr 4634  df-op 4638  df-br 5149  df-opab 5211  df-eprel 5589  df-xp 5695  df-rel 5696  df-cnv 5697  df-dm 5699  df-res 5701
This theorem is referenced by:  n0elim  38632  membpartlem19  38793
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