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Theorem elfv 5207
Description: Membership in a function value. (Contributed by NM, 30-Apr-2004.)
Assertion
Ref Expression
elfv  |-  ( A  e.  ( F `  B )  <->  E. x
( A  e.  x  /\  A. y ( B F y  <->  y  =  x ) ) )
Distinct variable groups:    x, A    x, y, B    x, F, y
Allowed substitution hint:    A( y)

Proof of Theorem elfv
StepHypRef Expression
1 fv2 5204 . . 3  |-  ( F `
 B )  = 
U. { x  | 
A. y ( B F y  <->  y  =  x ) }
21eleq2i 2146 . 2  |-  ( A  e.  ( F `  B )  <->  A  e.  U. { x  |  A. y ( B F y  <->  y  =  x ) } )
3 eluniab 3621 . 2  |-  ( A  e.  U. { x  |  A. y ( B F y  <->  y  =  x ) }  <->  E. x
( A  e.  x  /\  A. y ( B F y  <->  y  =  x ) ) )
42, 3bitri 182 1  |-  ( A  e.  ( F `  B )  <->  E. x
( A  e.  x  /\  A. y ( B F y  <->  y  =  x ) ) )
Colors of variables: wff set class
Syntax hints:    /\ wa 102    <-> wb 103   A.wal 1283   E.wex 1422    e. wcel 1434   {cab 2068   U.cuni 3609   class class class wbr 3793   ` cfv 4932
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 663  ax-5 1377  ax-7 1378  ax-gen 1379  ax-ie1 1423  ax-ie2 1424  ax-8 1436  ax-10 1437  ax-11 1438  ax-i12 1439  ax-bndl 1440  ax-4 1441  ax-17 1460  ax-i9 1464  ax-ial 1468  ax-i5r 1469  ax-ext 2064
This theorem depends on definitions:  df-bi 115  df-tru 1288  df-nf 1391  df-sb 1687  df-clab 2069  df-cleq 2075  df-clel 2078  df-nfc 2209  df-rex 2355  df-v 2604  df-sn 3412  df-uni 3610  df-iota 4897  df-fv 4940
This theorem is referenced by:  fv3  5229  relelfvdm  5237
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