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Theorem elreldm 4735
Description: The first member of an ordered pair in a relation belongs to the domain of the relation. (Contributed by NM, 28-Jul-2004.)
Assertion
Ref Expression
elreldm  |-  ( ( Rel  A  /\  B  e.  A )  ->  |^| |^| B  e.  dom  A )

Proof of Theorem elreldm
Dummy variables  x  y are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 df-rel 4516 . . . . 5  |-  ( Rel 
A  <->  A  C_  ( _V 
X.  _V ) )
2 ssel 3061 . . . . 5  |-  ( A 
C_  ( _V  X.  _V )  ->  ( B  e.  A  ->  B  e.  ( _V  X.  _V ) ) )
31, 2sylbi 120 . . . 4  |-  ( Rel 
A  ->  ( B  e.  A  ->  B  e.  ( _V  X.  _V ) ) )
4 elvv 4571 . . . 4  |-  ( B  e.  ( _V  X.  _V )  <->  E. x E. y  B  =  <. x ,  y >. )
53, 4syl6ib 160 . . 3  |-  ( Rel 
A  ->  ( B  e.  A  ->  E. x E. y  B  =  <. x ,  y >.
) )
6 eleq1 2180 . . . . . 6  |-  ( B  =  <. x ,  y
>.  ->  ( B  e.  A  <->  <. x ,  y
>.  e.  A ) )
7 vex 2663 . . . . . . 7  |-  x  e. 
_V
8 vex 2663 . . . . . . 7  |-  y  e. 
_V
97, 8opeldm 4712 . . . . . 6  |-  ( <.
x ,  y >.  e.  A  ->  x  e. 
dom  A )
106, 9syl6bi 162 . . . . 5  |-  ( B  =  <. x ,  y
>.  ->  ( B  e.  A  ->  x  e.  dom  A ) )
11 inteq 3744 . . . . . . . 8  |-  ( B  =  <. x ,  y
>.  ->  |^| B  =  |^| <.
x ,  y >.
)
1211inteqd 3746 . . . . . . 7  |-  ( B  =  <. x ,  y
>.  ->  |^| |^| B  =  |^| |^|
<. x ,  y >.
)
137, 8op1stb 4369 . . . . . . 7  |-  |^| |^| <. x ,  y >.  =  x
1412, 13syl6eq 2166 . . . . . 6  |-  ( B  =  <. x ,  y
>.  ->  |^| |^| B  =  x )
1514eleq1d 2186 . . . . 5  |-  ( B  =  <. x ,  y
>.  ->  ( |^| |^| B  e.  dom  A  <->  x  e.  dom  A ) )
1610, 15sylibrd 168 . . . 4  |-  ( B  =  <. x ,  y
>.  ->  ( B  e.  A  ->  |^| |^| B  e.  dom  A ) )
1716exlimivv 1852 . . 3  |-  ( E. x E. y  B  =  <. x ,  y
>.  ->  ( B  e.  A  ->  |^| |^| B  e.  dom  A ) )
185, 17syli 37 . 2  |-  ( Rel 
A  ->  ( B  e.  A  ->  |^| |^| B  e.  dom  A ) )
1918imp 123 1  |-  ( ( Rel  A  /\  B  e.  A )  ->  |^| |^| B  e.  dom  A )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ wa 103    = wceq 1316   E.wex 1453    e. wcel 1465   _Vcvv 2660    C_ wss 3041   <.cop 3500   |^|cint 3741    X. cxp 4507   dom cdm 4509   Rel wrel 4514
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  ax-pr 4101
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-ral 2398  df-v 2662  df-un 3045  df-in 3047  df-ss 3054  df-pw 3482  df-sn 3503  df-pr 3504  df-op 3506  df-int 3742  df-br 3900  df-opab 3960  df-xp 4515  df-rel 4516  df-dm 4519
This theorem is referenced by:  1stdm  6048  fundmen  6668
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