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Theorem opeqsn 4015
Description: Equivalence for an ordered pair equal to a singleton. (Contributed by NM, 3-Jun-2008.)
Hypotheses
Ref Expression
opeqsn.1  |-  A  e. 
_V
opeqsn.2  |-  B  e. 
_V
opeqsn.3  |-  C  e. 
_V
Assertion
Ref Expression
opeqsn  |-  ( <. A ,  B >.  =  { C }  <->  ( A  =  B  /\  C  =  { A } ) )

Proof of Theorem opeqsn
StepHypRef Expression
1 opeqsn.1 . . . 4  |-  A  e. 
_V
2 opeqsn.2 . . . 4  |-  B  e. 
_V
31, 2dfop 3577 . . 3  |-  <. A ,  B >.  =  { { A } ,  { A ,  B } }
43eqeq1i 2089 . 2  |-  ( <. A ,  B >.  =  { C }  <->  { { A } ,  { A ,  B } }  =  { C } )
51snex 3965 . . 3  |-  { A }  e.  _V
6 prexg 3974 . . . 4  |-  ( ( A  e.  _V  /\  B  e.  _V )  ->  { A ,  B }  e.  _V )
71, 2, 6mp2an 417 . . 3  |-  { A ,  B }  e.  _V
8 opeqsn.3 . . 3  |-  C  e. 
_V
95, 7, 8preqsn 3575 . 2  |-  ( { { A } ,  { A ,  B } }  =  { C } 
<->  ( { A }  =  { A ,  B }  /\  { A ,  B }  =  C
) )
10 eqcom 2084 . . . . 5  |-  ( { A }  =  { A ,  B }  <->  { A ,  B }  =  { A } )
111, 2, 1preqsn 3575 . . . . 5  |-  ( { A ,  B }  =  { A }  <->  ( A  =  B  /\  B  =  A ) )
12 eqcom 2084 . . . . . . 7  |-  ( B  =  A  <->  A  =  B )
1312anbi2i 445 . . . . . 6  |-  ( ( A  =  B  /\  B  =  A )  <->  ( A  =  B  /\  A  =  B )
)
14 anidm 388 . . . . . 6  |-  ( ( A  =  B  /\  A  =  B )  <->  A  =  B )
1513, 14bitri 182 . . . . 5  |-  ( ( A  =  B  /\  B  =  A )  <->  A  =  B )
1610, 11, 153bitri 204 . . . 4  |-  ( { A }  =  { A ,  B }  <->  A  =  B )
1716anbi1i 446 . . 3  |-  ( ( { A }  =  { A ,  B }  /\  { A ,  B }  =  C )  <->  ( A  =  B  /\  { A ,  B }  =  C ) )
18 dfsn2 3420 . . . . . . 7  |-  { A }  =  { A ,  A }
19 preq2 3478 . . . . . . 7  |-  ( A  =  B  ->  { A ,  A }  =  { A ,  B }
)
2018, 19syl5req 2127 . . . . . 6  |-  ( A  =  B  ->  { A ,  B }  =  { A } )
2120eqeq1d 2090 . . . . 5  |-  ( A  =  B  ->  ( { A ,  B }  =  C  <->  { A }  =  C ) )
22 eqcom 2084 . . . . 5  |-  ( { A }  =  C  <-> 
C  =  { A } )
2321, 22syl6bb 194 . . . 4  |-  ( A  =  B  ->  ( { A ,  B }  =  C  <->  C  =  { A } ) )
2423pm5.32i 442 . . 3  |-  ( ( A  =  B  /\  { A ,  B }  =  C )  <->  ( A  =  B  /\  C  =  { A } ) )
2517, 24bitri 182 . 2  |-  ( ( { A }  =  { A ,  B }  /\  { A ,  B }  =  C )  <->  ( A  =  B  /\  C  =  { A } ) )
264, 9, 253bitri 204 1  |-  ( <. A ,  B >.  =  { C }  <->  ( A  =  B  /\  C  =  { A } ) )
Colors of variables: wff set class
Syntax hints:    /\ wa 102    <-> wb 103    = wceq 1285    e. wcel 1434   _Vcvv 2602   {csn 3406   {cpr 3407   <.cop 3409
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 663  ax-5 1377  ax-7 1378  ax-gen 1379  ax-ie1 1423  ax-ie2 1424  ax-8 1436  ax-10 1437  ax-11 1438  ax-i12 1439  ax-bndl 1440  ax-4 1441  ax-14 1446  ax-17 1460  ax-i9 1464  ax-ial 1468  ax-i5r 1469  ax-ext 2064  ax-sep 3904  ax-pow 3956  ax-pr 3972
This theorem depends on definitions:  df-bi 115  df-3an 922  df-tru 1288  df-nf 1391  df-sb 1687  df-clab 2069  df-cleq 2075  df-clel 2078  df-nfc 2209  df-v 2604  df-un 2978  df-in 2980  df-ss 2987  df-pw 3392  df-sn 3412  df-pr 3413  df-op 3415
This theorem is referenced by:  relop  4514
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