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Theorem rexxfr 4772
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 2724 . 2  |-  ( E. x  e.  B  ph  <->  -. 
A. x  e.  B  -.  ph )
2 dfrex2 2724 . . 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 287 . . . 4  |-  ( x  =  A  ->  ( -.  ph  <->  -.  ps )
)
73, 4, 6ralxfr 4770 . . 3  |-  ( A. x  e.  B  -.  ph  <->  A. y  e.  C  -.  ps )
82, 7xchbinxr 304 . 2  |-  ( E. y  e.  C  ps  <->  -. 
A. x  e.  B  -.  ph )
91, 8bitr4i 245 1  |-  ( E. x  e.  B  ph  <->  E. y  e.  C  ps )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    <-> wb 178    = wceq 1653    e. wcel 1727   A.wral 2711   E.wrex 2712
This theorem is referenced by:  infm3  9998  reeff1o  20394  moxfr  26771
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1556  ax-5 1567  ax-17 1627  ax-9 1668  ax-8 1689  ax-6 1746  ax-7 1751  ax-11 1763  ax-12 1953  ax-ext 2423
This theorem depends on definitions:  df-bi 179  df-or 361  df-an 362  df-tru 1329  df-ex 1552  df-nf 1555  df-sb 1660  df-clab 2429  df-cleq 2435  df-clel 2438  df-nfc 2567  df-ral 2716  df-rex 2717  df-v 2964
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