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Theorem elfv 5685
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 5682 . . 3  |-  ( F `
 B )  = 
U. { x  | 
A. y ( B F y  <->  y  =  x ) }
21eleq2i 2468 . 2  |-  ( A  e.  ( F `  B )  <->  A  e.  U. { x  |  A. y ( B F y  <->  y  =  x ) } )
3 eluniab 3987 . 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 241 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:    <-> wb 177    /\ wa 359   A.wal 1546   E.wex 1547    e. wcel 1721   {cab 2390   U.cuni 3975   class class class wbr 4172   ` cfv 5413
This theorem is referenced by:  fv3  5703
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1552  ax-5 1563  ax-17 1623  ax-9 1662  ax-8 1683  ax-6 1740  ax-7 1745  ax-11 1757  ax-12 1946  ax-ext 2385
This theorem depends on definitions:  df-bi 178  df-an 361  df-tru 1325  df-ex 1548  df-nf 1551  df-sb 1656  df-clab 2391  df-cleq 2397  df-clel 2400  df-nfc 2529  df-rex 2672  df-v 2918  df-sn 3780  df-uni 3976  df-iota 5377  df-fv 5421
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