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Theorem f1stres 6157
Description: Mapping of a restriction of the  1st (first member of an ordered pair) function. (Contributed by NM, 11-Oct-2004.) (Revised by Mario Carneiro, 8-Sep-2013.)
Assertion
Ref Expression
f1stres  |-  ( 1st  |`  ( A  X.  B
) ) : ( A  X.  B ) --> A

Proof of Theorem f1stres
Dummy variables  x  y  z are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 vex 2804 . . . . . . . 8  |-  y  e. 
_V
2 vex 2804 . . . . . . . 8  |-  z  e. 
_V
31, 2op1sta 5170 . . . . . . 7  |-  U. dom  {
<. y ,  z >. }  =  y
43eleq1i 2359 . . . . . 6  |-  ( U. dom  { <. y ,  z
>. }  e.  A  <->  y  e.  A )
54biimpri 197 . . . . 5  |-  ( y  e.  A  ->  U. dom  {
<. y ,  z >. }  e.  A )
65adantr 451 . . . 4  |-  ( ( y  e.  A  /\  z  e.  B )  ->  U. dom  { <. y ,  z >. }  e.  A )
76rgen2 2652 . . 3  |-  A. y  e.  A  A. z  e.  B  U. dom  { <. y ,  z >. }  e.  A
8 sneq 3664 . . . . . . 7  |-  ( x  =  <. y ,  z
>.  ->  { x }  =  { <. y ,  z
>. } )
98dmeqd 4897 . . . . . 6  |-  ( x  =  <. y ,  z
>.  ->  dom  { x }  =  dom  { <. y ,  z >. } )
109unieqd 3854 . . . . 5  |-  ( x  =  <. y ,  z
>.  ->  U. dom  { x }  =  U. dom  { <. y ,  z >. } )
1110eleq1d 2362 . . . 4  |-  ( x  =  <. y ,  z
>.  ->  ( U. dom  { x }  e.  A  <->  U.
dom  { <. y ,  z
>. }  e.  A ) )
1211ralxp 4843 . . 3  |-  ( A. x  e.  ( A  X.  B ) U. dom  { x }  e.  A  <->  A. y  e.  A  A. z  e.  B  U. dom  { <. y ,  z
>. }  e.  A )
137, 12mpbir 200 . 2  |-  A. x  e.  ( A  X.  B
) U. dom  {
x }  e.  A
14 df-1st 6138 . . . . 5  |-  1st  =  ( x  e.  _V  |->  U.
dom  { x } )
1514reseq1i 4967 . . . 4  |-  ( 1st  |`  ( A  X.  B
) )  =  ( ( x  e.  _V  |->  U.
dom  { x } )  |`  ( A  X.  B
) )
16 ssv 3211 . . . . 5  |-  ( A  X.  B )  C_  _V
17 resmpt 5016 . . . . 5  |-  ( ( A  X.  B ) 
C_  _V  ->  ( ( x  e.  _V  |->  U.
dom  { x } )  |`  ( A  X.  B
) )  =  ( x  e.  ( A  X.  B )  |->  U.
dom  { x } ) )
1816, 17ax-mp 8 . . . 4  |-  ( ( x  e.  _V  |->  U.
dom  { x } )  |`  ( A  X.  B
) )  =  ( x  e.  ( A  X.  B )  |->  U.
dom  { x } )
1915, 18eqtri 2316 . . 3  |-  ( 1st  |`  ( A  X.  B
) )  =  ( x  e.  ( A  X.  B )  |->  U.
dom  { x } )
2019fmpt 5697 . 2  |-  ( A. x  e.  ( A  X.  B ) U. dom  { x }  e.  A  <->  ( 1st  |`  ( A  X.  B ) ) : ( A  X.  B
) --> A )
2113, 20mpbi 199 1  |-  ( 1st  |`  ( A  X.  B
) ) : ( A  X.  B ) --> A
Colors of variables: wff set class
Syntax hints:    = wceq 1632    e. wcel 1696   A.wral 2556   _Vcvv 2801    C_ wss 3165   {csn 3653   <.cop 3656   U.cuni 3843    e. cmpt 4093    X. cxp 4703   dom cdm 4705    |` cres 4707   -->wf 5267   1stc1st 6136
This theorem is referenced by:  fo1stres  6159  1stcof  6163  fparlem1  6234  domssex2  7037  domssex  7038  unxpwdom2  7318  1stfcl  13987  tx1cn  17319  xpinpreima  23305  xpinpreima2  23306  1stmbfm  23580  hausgraph  27634
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1536  ax-5 1547  ax-17 1606  ax-9 1644  ax-8 1661  ax-14 1700  ax-6 1715  ax-7 1720  ax-11 1727  ax-12 1878  ax-ext 2277  ax-sep 4157  ax-nul 4165  ax-pr 4230
This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-3an 936  df-tru 1310  df-ex 1532  df-nf 1535  df-sb 1639  df-eu 2160  df-mo 2161  df-clab 2283  df-cleq 2289  df-clel 2292  df-nfc 2421  df-ne 2461  df-ral 2561  df-rex 2562  df-rab 2565  df-v 2803  df-sbc 3005  df-csb 3095  df-dif 3168  df-un 3170  df-in 3172  df-ss 3179  df-nul 3469  df-if 3579  df-sn 3659  df-pr 3660  df-op 3662  df-uni 3844  df-iun 3923  df-br 4040  df-opab 4094  df-mpt 4095  df-id 4325  df-xp 4711  df-rel 4712  df-cnv 4713  df-co 4714  df-dm 4715  df-rn 4716  df-res 4717  df-ima 4718  df-iota 5235  df-fun 5273  df-fn 5274  df-f 5275  df-fv 5279  df-1st 6138
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