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Theorem elpr 3462
Description: A member of an unordered pair of classes is one or the other of them. Exercise 1 of [TakeutiZaring] p. 15. (Contributed by NM, 13-Sep-1995.)
Hypothesis
Ref Expression
elpr.1  |-  A  e. 
_V
Assertion
Ref Expression
elpr  |-  ( A  e.  { B ,  C }  <->  ( A  =  B  \/  A  =  C ) )

Proof of Theorem elpr
StepHypRef Expression
1 elpr.1 . 2  |-  A  e. 
_V
2 elprg 3461 . 2  |-  ( A  e.  _V  ->  ( A  e.  { B ,  C }  <->  ( A  =  B  \/  A  =  C ) ) )
31, 2ax-mp 7 1  |-  ( A  e.  { B ,  C }  <->  ( A  =  B  \/  A  =  C ) )
Colors of variables: wff set class
Syntax hints:    <-> wb 103    \/ wo 664    = wceq 1289    e. wcel 1438   _Vcvv 2619   {cpr 3442
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 665  ax-5 1381  ax-7 1382  ax-gen 1383  ax-ie1 1427  ax-ie2 1428  ax-8 1440  ax-10 1441  ax-11 1442  ax-i12 1443  ax-bndl 1444  ax-4 1445  ax-17 1464  ax-i9 1468  ax-ial 1472  ax-i5r 1473  ax-ext 2070
This theorem depends on definitions:  df-bi 115  df-tru 1292  df-nf 1395  df-sb 1693  df-clab 2075  df-cleq 2081  df-clel 2084  df-nfc 2217  df-v 2621  df-un 3001  df-sn 3447  df-pr 3448
This theorem is referenced by:  prmg  3556  difprsnss  3570  preqr1  3607  preq12b  3609  prel12  3610  pwprss  3644  pwtpss  3645  unipr  3662  intpr  3715  zfpair2  4028  elop  4049  ordtri2or2exmidlem  4332  onsucelsucexmidlem  4335  en2lp  4360  reg3exmidlemwe  4384  xpsspw  4538  acexmidlem2  5631  2oconcl  6185  exmidpw  6604  renfdisj  7525  fzpr  9458  maxabslemval  10606  isprm2  11192  bj-zfpair2  11458  ss1oel2o  11545
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