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Theorem opthpr 3571
Description: A way to represent ordered pairs using unordered pairs with distinct members. (Contributed by NM, 27-Mar-2007.)
Hypotheses
Ref Expression
preq12b.1  |-  A  e. 
_V
preq12b.2  |-  B  e. 
_V
preq12b.3  |-  C  e. 
_V
preq12b.4  |-  D  e. 
_V
Assertion
Ref Expression
opthpr  |-  ( A  =/=  D  ->  ( { A ,  B }  =  { C ,  D } 
<->  ( A  =  C  /\  B  =  D ) ) )

Proof of Theorem opthpr
StepHypRef Expression
1 preq12b.1 . . 3  |-  A  e. 
_V
2 preq12b.2 . . 3  |-  B  e. 
_V
3 preq12b.3 . . 3  |-  C  e. 
_V
4 preq12b.4 . . 3  |-  D  e. 
_V
51, 2, 3, 4preq12b 3569 . 2  |-  ( { A ,  B }  =  { C ,  D } 
<->  ( ( A  =  C  /\  B  =  D )  \/  ( A  =  D  /\  B  =  C )
) )
6 idd 21 . . . 4  |-  ( A  =/=  D  ->  (
( A  =  C  /\  B  =  D )  ->  ( A  =  C  /\  B  =  D ) ) )
7 df-ne 2221 . . . . . 6  |-  ( A  =/=  D  <->  -.  A  =  D )
8 pm2.21 557 . . . . . 6  |-  ( -.  A  =  D  -> 
( A  =  D  ->  ( B  =  C  ->  ( A  =  C  /\  B  =  D ) ) ) )
97, 8sylbi 118 . . . . 5  |-  ( A  =/=  D  ->  ( A  =  D  ->  ( B  =  C  -> 
( A  =  C  /\  B  =  D ) ) ) )
109impd 246 . . . 4  |-  ( A  =/=  D  ->  (
( A  =  D  /\  B  =  C )  ->  ( A  =  C  /\  B  =  D ) ) )
116, 10jaod 647 . . 3  |-  ( A  =/=  D  ->  (
( ( A  =  C  /\  B  =  D )  \/  ( A  =  D  /\  B  =  C )
)  ->  ( A  =  C  /\  B  =  D ) ) )
12 orc 643 . . 3  |-  ( ( A  =  C  /\  B  =  D )  ->  ( ( A  =  C  /\  B  =  D )  \/  ( A  =  D  /\  B  =  C )
) )
1311, 12impbid1 134 . 2  |-  ( A  =/=  D  ->  (
( ( A  =  C  /\  B  =  D )  \/  ( A  =  D  /\  B  =  C )
)  <->  ( A  =  C  /\  B  =  D ) ) )
145, 13syl5bb 185 1  |-  ( A  =/=  D  ->  ( { A ,  B }  =  { C ,  D } 
<->  ( A  =  C  /\  B  =  D ) ) )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    /\ wa 101    <-> wb 102    \/ wo 639    = wceq 1259    e. wcel 1409    =/= wne 2220   _Vcvv 2574   {cpr 3404
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-in2 555  ax-io 640  ax-5 1352  ax-7 1353  ax-gen 1354  ax-ie1 1398  ax-ie2 1399  ax-8 1411  ax-10 1412  ax-11 1413  ax-i12 1414  ax-bndl 1415  ax-4 1416  ax-17 1435  ax-i9 1439  ax-ial 1443  ax-i5r 1444  ax-ext 2038
This theorem depends on definitions:  df-bi 114  df-tru 1262  df-nf 1366  df-sb 1662  df-clab 2043  df-cleq 2049  df-clel 2052  df-nfc 2183  df-ne 2221  df-v 2576  df-un 2950  df-sn 3409  df-pr 3410
This theorem is referenced by: (None)
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