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Theorem opi1 4124
Description: One of the two elements in an ordered pair. (Contributed by NM, 5-Aug-1993.) (Revised by Mario Carneiro, 26-Apr-2015.)
Hypotheses
Ref Expression
opi1.1  |-  A  e. 
_V
opi1.2  |-  B  e. 
_V
Assertion
Ref Expression
opi1  |-  { A }  e.  <. A ,  B >.

Proof of Theorem opi1
StepHypRef Expression
1 opi1.1 . . . 4  |-  A  e. 
_V
21snex 4079 . . 3  |-  { A }  e.  _V
32prid1 3599 . 2  |-  { A }  e.  { { A } ,  { A ,  B } }
4 opi1.2 . . 3  |-  B  e. 
_V
51, 4dfop 3674 . 2  |-  <. A ,  B >.  =  { { A } ,  { A ,  B } }
63, 5eleqtrri 2193 1  |-  { A }  e.  <. A ,  B >.
Colors of variables: wff set class
Syntax hints:    e. wcel 1465   _Vcvv 2660   {csn 3497   {cpr 3498   <.cop 3500
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 683  ax-5 1408  ax-7 1409  ax-gen 1410  ax-ie1 1454  ax-ie2 1455  ax-8 1467  ax-10 1468  ax-11 1469  ax-i12 1470  ax-bndl 1471  ax-4 1472  ax-14 1477  ax-17 1491  ax-i9 1495  ax-ial 1499  ax-i5r 1500  ax-ext 2099  ax-sep 4016  ax-pow 4068
This theorem depends on definitions:  df-bi 116  df-3an 949  df-tru 1319  df-nf 1422  df-sb 1721  df-clab 2104  df-cleq 2110  df-clel 2113  df-nfc 2247  df-v 2662  df-un 3045  df-in 3047  df-ss 3054  df-pw 3482  df-sn 3503  df-pr 3504  df-op 3506
This theorem is referenced by:  opth1  4128  opth  4129
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