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Theorem elnev 38459
 Description: Any set that contains one element less than the universe is not equal to it. (Contributed by Andrew Salmon, 16-Jun-2011.)
Assertion
Ref Expression
elnev (𝐴 ∈ V ↔ {𝑥 ∣ ¬ 𝑥 = 𝐴} ≠ V)
Distinct variable group:   𝑥,𝐴

Proof of Theorem elnev
StepHypRef Expression
1 isset 3202 . 2 (𝐴 ∈ V ↔ ∃𝑥 𝑥 = 𝐴)
2 df-v 3197 . . . . 5 V = {𝑥𝑥 = 𝑥}
32eqeq2i 2632 . . . 4 ({𝑥 ∣ ¬ 𝑥 = 𝐴} = V ↔ {𝑥 ∣ ¬ 𝑥 = 𝐴} = {𝑥𝑥 = 𝑥})
4 equid 1937 . . . . . . 7 𝑥 = 𝑥
54tbt 359 . . . . . 6 𝑥 = 𝐴 ↔ (¬ 𝑥 = 𝐴𝑥 = 𝑥))
65albii 1745 . . . . 5 (∀𝑥 ¬ 𝑥 = 𝐴 ↔ ∀𝑥𝑥 = 𝐴𝑥 = 𝑥))
7 alnex 1704 . . . . 5 (∀𝑥 ¬ 𝑥 = 𝐴 ↔ ¬ ∃𝑥 𝑥 = 𝐴)
8 abbi 2735 . . . . 5 (∀𝑥𝑥 = 𝐴𝑥 = 𝑥) ↔ {𝑥 ∣ ¬ 𝑥 = 𝐴} = {𝑥𝑥 = 𝑥})
96, 7, 83bitr3ri 291 . . . 4 ({𝑥 ∣ ¬ 𝑥 = 𝐴} = {𝑥𝑥 = 𝑥} ↔ ¬ ∃𝑥 𝑥 = 𝐴)
103, 9bitri 264 . . 3 ({𝑥 ∣ ¬ 𝑥 = 𝐴} = V ↔ ¬ ∃𝑥 𝑥 = 𝐴)
1110necon2abii 2841 . 2 (∃𝑥 𝑥 = 𝐴 ↔ {𝑥 ∣ ¬ 𝑥 = 𝐴} ≠ V)
121, 11bitri 264 1 (𝐴 ∈ V ↔ {𝑥 ∣ ¬ 𝑥 = 𝐴} ≠ V)
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   ↔ wb 196  ∀wal 1479   = wceq 1481  ∃wex 1702   ∈ wcel 1988  {cab 2606   ≠ wne 2791  Vcvv 3195 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1720  ax-4 1735  ax-5 1837  ax-6 1886  ax-7 1933  ax-9 1997  ax-10 2017  ax-11 2032  ax-12 2045  ax-13 2244  ax-ext 2600 This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-tru 1484  df-ex 1703  df-nf 1708  df-sb 1879  df-clab 2607  df-cleq 2613  df-clel 2616  df-ne 2792  df-v 3197 This theorem is referenced by: (None)
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