Theorem elpr 3614

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 3613	. 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 708   = wceq 1353   e. wcel 2148   _Vcvv 2738   {cpr 3594

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 709  ax-5 1447  ax-7 1448  ax-gen 1449  ax-ie1 1493  ax-ie2 1494  ax-8 1504  ax-10 1505  ax-11 1506  ax-i12 1507  ax-bndl 1509  ax-4 1510  ax-17 1526  ax-i9 1530  ax-ial 1534  ax-i5r 1535  ax-ext 2159

This theorem depends on definitions:  df-bi 117  df-tru 1356  df-nf 1461  df-sb 1763  df-clab 2164  df-cleq 2170  df-clel 2173  df-nfc 2308  df-v 2740  df-un 3134  df-sn 3599  df-pr 3600

This theorem is referenced by:  prmg  3714  difprsnss  3731  preqr1  3769  preq12b  3771  prel12  3772  pwprss  3806  pwtpss  3807  unipr  3824  intpr  3877  zfpair2  4211  elop  4232  ordtri2or2exmidlem  4526  onsucelsucexmidlem  4529  en2lp  4554  reg3exmidlemwe  4579  xpsspw  4739  acexmidlem2  5872  2oconcl  6440  exmidpw  6908  exmidpweq  6909  renfdisj  8017  fzpr  10077  maxabslemval  11217  xrmaxiflemval  11258  isprm2  12117  bj-zfpair2  14665  ss1oel2o  14746