Theorem elpr 3604

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 3603	. 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 104   \/ wo 703   = wceq 1348   e. wcel 2141   _Vcvv 2730   {cpr 3584

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 704  ax-5 1440  ax-7 1441  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-10 1498  ax-11 1499  ax-i12 1500  ax-bndl 1502  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-i5r 1528  ax-ext 2152

This theorem depends on definitions:  df-bi 116  df-tru 1351  df-nf 1454  df-sb 1756  df-clab 2157  df-cleq 2163  df-clel 2166  df-nfc 2301  df-v 2732  df-un 3125  df-sn 3589  df-pr 3590

This theorem is referenced by:  prmg  3704  difprsnss  3718  preqr1  3755  preq12b  3757  prel12  3758  pwprss  3792  pwtpss  3793  unipr  3810  intpr  3863  zfpair2  4195  elop  4216  ordtri2or2exmidlem  4510  onsucelsucexmidlem  4513  en2lp  4538  reg3exmidlemwe  4563  xpsspw  4723  acexmidlem2  5850  2oconcl  6418  exmidpw  6886  exmidpweq  6887  renfdisj  7979  fzpr  10033  maxabslemval  11172  xrmaxiflemval  11213  isprm2  12071  bj-zfpair2  13945  ss1oel2o  14026