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Theorem rexxfr 4706
Description: Transfer existence from a variable  x to another variable  y contained in expression  A. (Contributed by NM, 10-Jun-2005.) (Revised by Mario Carneiro, 15-Aug-2014.)
Hypotheses
Ref Expression
ralxfr.1  |-  ( y  e.  C  ->  A  e.  B )
ralxfr.2  |-  ( x  e.  B  ->  E. y  e.  C  x  =  A )
ralxfr.3  |-  ( x  =  A  ->  ( ph 
<->  ps ) )
Assertion
Ref Expression
rexxfr  |-  ( E. x  e.  B  ph  <->  E. y  e.  C  ps )
Distinct variable groups:    ps, x    ph, y    x, A    x, y, B    x, C
Allowed substitution hints:    ph( x)    ps( y)    A( y)    C( y)

Proof of Theorem rexxfr
StepHypRef Expression
1 dfrex2 2683 . 2  |-  ( E. x  e.  B  ph  <->  -. 
A. x  e.  B  -.  ph )
2 dfrex2 2683 . . 3  |-  ( E. y  e.  C  ps  <->  -. 
A. y  e.  C  -.  ps )
3 ralxfr.1 . . . 4  |-  ( y  e.  C  ->  A  e.  B )
4 ralxfr.2 . . . 4  |-  ( x  e.  B  ->  E. y  e.  C  x  =  A )
5 ralxfr.3 . . . . 5  |-  ( x  =  A  ->  ( ph 
<->  ps ) )
65notbid 286 . . . 4  |-  ( x  =  A  ->  ( -.  ph  <->  -.  ps )
)
73, 4, 6ralxfr 4704 . . 3  |-  ( A. x  e.  B  -.  ph  <->  A. y  e.  C  -.  ps )
82, 7xchbinxr 303 . 2  |-  ( E. y  e.  C  ps  <->  -. 
A. x  e.  B  -.  ph )
91, 8bitr4i 244 1  |-  ( E. x  e.  B  ph  <->  E. y  e.  C  ps )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    <-> wb 177    = wceq 1649    e. wcel 1721   A.wral 2670   E.wrex 2671
This theorem is referenced by:  infm3  9927  reeff1o  20320  moxfr  26627
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 2389
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 2395  df-cleq 2401  df-clel 2404  df-nfc 2533  df-ral 2675  df-rex 2676  df-v 2922
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