Theorem elpr 3687

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

Step	Hyp	Ref	Expression
1		elpr.1	. 2 |- A e. _V
2		elprg 3686	. 2 |- ( A e. _V -> ( A e. { B , C } <-> ( A = B \/ A = C ) ) )
3	1, 2	ax-mp 5	1 |- ( A e. { B , C } <-> ( A = B \/ A = C ) )

Syntax hints:   <-> wb 105   \/ wo 713   = wceq 1395   e. wcel 2200   _Vcvv 2799   {cpr 3667

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 714  ax-5 1493  ax-7 1494  ax-gen 1495  ax-ie1 1539  ax-ie2 1540  ax-8 1550  ax-10 1551  ax-11 1552  ax-i12 1553  ax-bndl 1555  ax-4 1556  ax-17 1572  ax-i9 1576  ax-ial 1580  ax-i5r 1581  ax-ext 2211

This theorem depends on definitions:  df-bi 117  df-tru 1398  df-nf 1507  df-sb 1809  df-clab 2216  df-cleq 2222  df-clel 2225  df-nfc 2361  df-v 2801  df-un 3201  df-sn 3672  df-pr 3673

This theorem is referenced by:  prmg  3789  difprsnss  3806  preqr1  3846  preq12b  3848  prel12  3849  pwprss  3884  pwtpss  3885  unipr  3902  intpr  3955  zfpair2  4294  elop  4317  ordtri2or2exmidlem  4618  onsucelsucexmidlem  4621  en2lp  4646  reg3exmidlemwe  4671  xpsspw  4831  acexmidlem2  5998  2oconcl  6585  exmidpw  7070  exmidpweq  7071  renfdisj  8206  fzpr  10273  maxabslemval  11719  xrmaxiflemval  11761  isprm2  12639  2lgslem4  15782  structiedg0val  15841  bj-zfpair2  16273  ss1oel2o  16355