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Theorem dfiun3g 4686
Description: Alternate definition of indexed union when  B is a set. (Contributed by Mario Carneiro, 31-Aug-2015.)
Assertion
Ref Expression
dfiun3g  |-  ( A. x  e.  A  B  e.  C  ->  U_ x  e.  A  B  =  U. ran  ( x  e.  A  |->  B ) )

Proof of Theorem dfiun3g
Dummy variable  y is distinct from all other variables.
StepHypRef Expression
1 dfiun2g 3760 . 2  |-  ( A. x  e.  A  B  e.  C  ->  U_ x  e.  A  B  =  U. { y  |  E. x  e.  A  y  =  B } )
2 eqid 2088 . . . 4  |-  ( x  e.  A  |->  B )  =  ( x  e.  A  |->  B )
32rnmpt 4679 . . 3  |-  ran  (
x  e.  A  |->  B )  =  { y  |  E. x  e.  A  y  =  B }
43unieqi 3661 . 2  |-  U. ran  ( x  e.  A  |->  B )  =  U. { y  |  E. x  e.  A  y  =  B }
51, 4syl6eqr 2138 1  |-  ( A. x  e.  A  B  e.  C  ->  U_ x  e.  A  B  =  U. ran  ( x  e.  A  |->  B ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    = wceq 1289    e. wcel 1438   {cab 2074   A.wral 2359   E.wrex 2360   U.cuni 3651   U_ciun 3728    |-> cmpt 3897   ran crn 4437
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 665  ax-5 1381  ax-7 1382  ax-gen 1383  ax-ie1 1427  ax-ie2 1428  ax-8 1440  ax-10 1441  ax-11 1442  ax-i12 1443  ax-bndl 1444  ax-4 1445  ax-14 1450  ax-17 1464  ax-i9 1468  ax-ial 1472  ax-i5r 1473  ax-ext 2070  ax-sep 3955  ax-pow 4007  ax-pr 4034
This theorem depends on definitions:  df-bi 115  df-3an 926  df-tru 1292  df-nf 1395  df-sb 1693  df-eu 1951  df-mo 1952  df-clab 2075  df-cleq 2081  df-clel 2084  df-nfc 2217  df-ral 2364  df-rex 2365  df-v 2621  df-un 3003  df-in 3005  df-ss 3012  df-pw 3429  df-sn 3450  df-pr 3451  df-op 3453  df-uni 3652  df-iun 3730  df-br 3844  df-opab 3898  df-mpt 3899  df-cnv 4444  df-dm 4446  df-rn 4447
This theorem is referenced by:  dfiun3  4688  iunon  6041
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