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Theorem preq12bg 3979
Description: Closed form of preq12b 3976. (Contributed by Scott Fenton, 28-Mar-2014.)
Assertion
Ref Expression
preq12bg  |-  ( ( ( A  e.  V  /\  B  e.  W
)  /\  ( C  e.  X  /\  D  e.  Y ) )  -> 
( { A ,  B }  =  { C ,  D }  <->  ( ( A  =  C  /\  B  =  D )  \/  ( A  =  D  /\  B  =  C ) ) ) )

Proof of Theorem preq12bg
Dummy variables  x  y  z  w are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 preq1 3885 . . . . . . 7  |-  ( x  =  A  ->  { x ,  y }  =  { A ,  y } )
21eqeq1d 2446 . . . . . 6  |-  ( x  =  A  ->  ( { x ,  y }  =  { z ,  D }  <->  { A ,  y }  =  { z ,  D } ) )
3 eqeq1 2444 . . . . . . . 8  |-  ( x  =  A  ->  (
x  =  z  <->  A  =  z ) )
43anbi1d 687 . . . . . . 7  |-  ( x  =  A  ->  (
( x  =  z  /\  y  =  D )  <->  ( A  =  z  /\  y  =  D ) ) )
5 eqeq1 2444 . . . . . . . 8  |-  ( x  =  A  ->  (
x  =  D  <->  A  =  D ) )
65anbi1d 687 . . . . . . 7  |-  ( x  =  A  ->  (
( x  =  D  /\  y  =  z )  <->  ( A  =  D  /\  y  =  z ) ) )
74, 6orbi12d 692 . . . . . 6  |-  ( x  =  A  ->  (
( ( x  =  z  /\  y  =  D )  \/  (
x  =  D  /\  y  =  z )
)  <->  ( ( A  =  z  /\  y  =  D )  \/  ( A  =  D  /\  y  =  z )
) ) )
82, 7bibi12d 314 . . . . 5  |-  ( x  =  A  ->  (
( { x ,  y }  =  {
z ,  D }  <->  ( ( x  =  z  /\  y  =  D )  \/  ( x  =  D  /\  y  =  z ) ) )  <->  ( { A ,  y }  =  { z ,  D } 
<->  ( ( A  =  z  /\  y  =  D )  \/  ( A  =  D  /\  y  =  z )
) ) ) )
98imbi2d 309 . . . 4  |-  ( x  =  A  ->  (
( D  e.  Y  ->  ( { x ,  y }  =  {
z ,  D }  <->  ( ( x  =  z  /\  y  =  D )  \/  ( x  =  D  /\  y  =  z ) ) ) )  <->  ( D  e.  Y  ->  ( { A ,  y }  =  { z ,  D }  <->  ( ( A  =  z  /\  y  =  D )  \/  ( A  =  D  /\  y  =  z ) ) ) ) ) )
10 preq2 3886 . . . . . . 7  |-  ( y  =  B  ->  { A ,  y }  =  { A ,  B }
)
1110eqeq1d 2446 . . . . . 6  |-  ( y  =  B  ->  ( { A ,  y }  =  { z ,  D }  <->  { A ,  B }  =  {
z ,  D }
) )
12 eqeq1 2444 . . . . . . . 8  |-  ( y  =  B  ->  (
y  =  D  <->  B  =  D ) )
1312anbi2d 686 . . . . . . 7  |-  ( y  =  B  ->  (
( A  =  z  /\  y  =  D )  <->  ( A  =  z  /\  B  =  D ) ) )
14 eqeq1 2444 . . . . . . . 8  |-  ( y  =  B  ->  (
y  =  z  <->  B  =  z ) )
1514anbi2d 686 . . . . . . 7  |-  ( y  =  B  ->  (
( A  =  D  /\  y  =  z )  <->  ( A  =  D  /\  B  =  z ) ) )
1613, 15orbi12d 692 . . . . . 6  |-  ( y  =  B  ->  (
( ( A  =  z  /\  y  =  D )  \/  ( A  =  D  /\  y  =  z )
)  <->  ( ( A  =  z  /\  B  =  D )  \/  ( A  =  D  /\  B  =  z )
) ) )
1711, 16bibi12d 314 . . . . 5  |-  ( y  =  B  ->  (
( { A , 
y }  =  {
z ,  D }  <->  ( ( A  =  z  /\  y  =  D )  \/  ( A  =  D  /\  y  =  z ) ) )  <->  ( { A ,  B }  =  {
z ,  D }  <->  ( ( A  =  z  /\  B  =  D )  \/  ( A  =  D  /\  B  =  z ) ) ) ) )
1817imbi2d 309 . . . 4  |-  ( y  =  B  ->  (
( D  e.  Y  ->  ( { A , 
y }  =  {
z ,  D }  <->  ( ( A  =  z  /\  y  =  D )  \/  ( A  =  D  /\  y  =  z ) ) ) )  <->  ( D  e.  Y  ->  ( { A ,  B }  =  { z ,  D } 
<->  ( ( A  =  z  /\  B  =  D )  \/  ( A  =  D  /\  B  =  z )
) ) ) ) )
19 preq1 3885 . . . . . . 7  |-  ( z  =  C  ->  { z ,  D }  =  { C ,  D }
)
2019eqeq2d 2449 . . . . . 6  |-  ( z  =  C  ->  ( { A ,  B }  =  { z ,  D } 
<->  { A ,  B }  =  { C ,  D } ) )
21 eqeq2 2447 . . . . . . . 8  |-  ( z  =  C  ->  ( A  =  z  <->  A  =  C ) )
2221anbi1d 687 . . . . . . 7  |-  ( z  =  C  ->  (
( A  =  z  /\  B  =  D )  <->  ( A  =  C  /\  B  =  D ) ) )
23 eqeq2 2447 . . . . . . . 8  |-  ( z  =  C  ->  ( B  =  z  <->  B  =  C ) )
2423anbi2d 686 . . . . . . 7  |-  ( z  =  C  ->  (
( A  =  D  /\  B  =  z )  <->  ( A  =  D  /\  B  =  C ) ) )
2522, 24orbi12d 692 . . . . . 6  |-  ( z  =  C  ->  (
( ( A  =  z  /\  B  =  D )  \/  ( A  =  D  /\  B  =  z )
)  <->  ( ( A  =  C  /\  B  =  D )  \/  ( A  =  D  /\  B  =  C )
) ) )
2620, 25bibi12d 314 . . . . 5  |-  ( z  =  C  ->  (
( { A ,  B }  =  {
z ,  D }  <->  ( ( A  =  z  /\  B  =  D )  \/  ( A  =  D  /\  B  =  z ) ) )  <->  ( { A ,  B }  =  { C ,  D }  <->  ( ( A  =  C  /\  B  =  D )  \/  ( A  =  D  /\  B  =  C ) ) ) ) )
2726imbi2d 309 . . . 4  |-  ( z  =  C  ->  (
( D  e.  Y  ->  ( { A ,  B }  =  {
z ,  D }  <->  ( ( A  =  z  /\  B  =  D )  \/  ( A  =  D  /\  B  =  z ) ) ) )  <->  ( D  e.  Y  ->  ( { A ,  B }  =  { C ,  D } 
<->  ( ( A  =  C  /\  B  =  D )  \/  ( A  =  D  /\  B  =  C )
) ) ) ) )
28 preq2 3886 . . . . . . 7  |-  ( w  =  D  ->  { z ,  w }  =  { z ,  D } )
2928eqeq2d 2449 . . . . . 6  |-  ( w  =  D  ->  ( { x ,  y }  =  { z ,  w }  <->  { x ,  y }  =  { z ,  D } ) )
30 eqeq2 2447 . . . . . . . 8  |-  ( w  =  D  ->  (
y  =  w  <->  y  =  D ) )
3130anbi2d 686 . . . . . . 7  |-  ( w  =  D  ->  (
( x  =  z  /\  y  =  w )  <->  ( x  =  z  /\  y  =  D ) ) )
32 eqeq2 2447 . . . . . . . 8  |-  ( w  =  D  ->  (
x  =  w  <->  x  =  D ) )
3332anbi1d 687 . . . . . . 7  |-  ( w  =  D  ->  (
( x  =  w  /\  y  =  z )  <->  ( x  =  D  /\  y  =  z ) ) )
3431, 33orbi12d 692 . . . . . 6  |-  ( w  =  D  ->  (
( ( x  =  z  /\  y  =  w )  \/  (
x  =  w  /\  y  =  z )
)  <->  ( ( x  =  z  /\  y  =  D )  \/  (
x  =  D  /\  y  =  z )
) ) )
35 vex 2961 . . . . . . 7  |-  x  e. 
_V
36 vex 2961 . . . . . . 7  |-  y  e. 
_V
37 vex 2961 . . . . . . 7  |-  z  e. 
_V
38 vex 2961 . . . . . . 7  |-  w  e. 
_V
3935, 36, 37, 38preq12b 3976 . . . . . 6  |-  ( { x ,  y }  =  { z ,  w }  <->  ( (
x  =  z  /\  y  =  w )  \/  ( x  =  w  /\  y  =  z ) ) )
4029, 34, 39vtoclbg 3014 . . . . 5  |-  ( D  e.  Y  ->  ( { x ,  y }  =  { z ,  D }  <->  ( (
x  =  z  /\  y  =  D )  \/  ( x  =  D  /\  y  =  z ) ) ) )
4140a1i 11 . . . 4  |-  ( ( x  e.  V  /\  y  e.  W  /\  z  e.  X )  ->  ( D  e.  Y  ->  ( { x ,  y }  =  {
z ,  D }  <->  ( ( x  =  z  /\  y  =  D )  \/  ( x  =  D  /\  y  =  z ) ) ) ) )
429, 18, 27, 41vtocl3ga 3023 . . 3  |-  ( ( A  e.  V  /\  B  e.  W  /\  C  e.  X )  ->  ( D  e.  Y  ->  ( { A ,  B }  =  { C ,  D }  <->  ( ( A  =  C  /\  B  =  D )  \/  ( A  =  D  /\  B  =  C ) ) ) ) )
43423expa 1154 . 2  |-  ( ( ( A  e.  V  /\  B  e.  W
)  /\  C  e.  X )  ->  ( D  e.  Y  ->  ( { A ,  B }  =  { C ,  D }  <->  ( ( A  =  C  /\  B  =  D )  \/  ( A  =  D  /\  B  =  C ) ) ) ) )
4443impr 604 1  |-  ( ( ( A  e.  V  /\  B  e.  W
)  /\  ( C  e.  X  /\  D  e.  Y ) )  -> 
( { A ,  B }  =  { C ,  D }  <->  ( ( A  =  C  /\  B  =  D )  \/  ( A  =  D  /\  B  =  C ) ) ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 178    \/ wo 359    /\ wa 360    /\ w3a 937    = wceq 1653    e. wcel 1726   {cpr 3817
This theorem is referenced by:  prneimg  3980  pythagtriplem2  13193  pythagtrip  13210  usgraidx2v  21414  constr3trllem2  21640  preqsnd  24002  pr1eqbg  28058  usgra2wlkspthlem1  28332  usgra2adedgspthlem2  28340
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1556  ax-5 1567  ax-17 1627  ax-9 1667  ax-8 1688  ax-6 1745  ax-7 1750  ax-11 1762  ax-12 1951  ax-ext 2419
This theorem depends on definitions:  df-bi 179  df-or 361  df-an 362  df-3an 939  df-tru 1329  df-ex 1552  df-nf 1555  df-sb 1660  df-clab 2425  df-cleq 2431  df-clel 2434  df-nfc 2563  df-v 2960  df-un 3327  df-sn 3822  df-pr 3823
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