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Theorem eq0 2284
Description: The empty set has no elements. Theorem 2 of [Suppes] p. 22.
Assertion
Ref Expression
eq0 |- (A = (/) <-> A.x -. x e. A)
Distinct variable group:   x,A

Proof of Theorem eq0
StepHypRef Expression
1 n0 2279 . . 3 |- (-. A = (/) <-> E.x x e. A)
2 df-ex 978 . . 3 |- (E.x x e. A <-> -. A.x -. x e. A)
31, 2bitr 173 . 2 |- (-. A = (/) <-> -. A.x -. x e. A)
43con4bii 521 1 |- (A = (/) <-> A.x -. x e. A)
Colors of variables: wff set class
Syntax hints:  -. wn 2   <-> wb 146  A.wal 951   = wceq 953   e. wcel 955  E.wex 977  (/)c0 2270
This theorem is referenced by:  0el 2286  ssdif0 2317  difin0ss 2322  inssdif0 2323  ralf0 2349  0ex 2701  snex 2740  reldm0 3320  tz6.12-2 3724  uzwo4OLD 6158  uzwo 6387  uzwoOLD 6388
This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7  ax-7 959  ax-gen 960  ax-8 961  ax-10 963  ax-12 965  ax-17 968  ax-4 970  ax-5o 972  ax-6o 975  ax-9o 1119  ax-10o 1136  ax-16 1206  ax-11o 1213  ax-ext 1452
This theorem depends on definitions:  df-bi 147  df-or 224  df-an 225  df-ex 978  df-sb 1168  df-clab 1457  df-cleq 1462  df-clel 1465  df-ne 1579  df-v 1803  df-dif 2039  df-nul 2271
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