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Theorem cbvrexf 3076
Description: Rule used to change bound variables, using implicit substitution. (Contributed by FL, 27-Apr-2008.) (Revised by Mario Carneiro, 9-Oct-2016.)
Hypotheses
Ref Expression
cbvralf.1  |-  F/_ x A
cbvralf.2  |-  F/_ y A
cbvralf.3  |-  F/ y
ph
cbvralf.4  |-  F/ x ps
cbvralf.5  |-  ( x  =  y  ->  ( ph 
<->  ps ) )
Assertion
Ref Expression
cbvrexf  |-  ( E. x  e.  A  ph  <->  E. y  e.  A  ps )

Proof of Theorem cbvrexf
StepHypRef Expression
1 cbvralf.1 . . . 4  |-  F/_ x A
2 cbvralf.2 . . . 4  |-  F/_ y A
3 cbvralf.3 . . . . 5  |-  F/ y
ph
43nfn 1906 . . . 4  |-  F/ y  -.  ph
5 cbvralf.4 . . . . 5  |-  F/ x ps
65nfn 1906 . . . 4  |-  F/ x  -.  ps
7 cbvralf.5 . . . . 5  |-  ( x  =  y  ->  ( ph 
<->  ps ) )
87notbid 292 . . . 4  |-  ( x  =  y  ->  ( -.  ph  <->  -.  ps )
)
91, 2, 4, 6, 8cbvralf 3075 . . 3  |-  ( A. x  e.  A  -.  ph  <->  A. y  e.  A  -.  ps )
109notbii 294 . 2  |-  ( -. 
A. x  e.  A  -.  ph  <->  -.  A. y  e.  A  -.  ps )
11 dfrex2 2905 . 2  |-  ( E. x  e.  A  ph  <->  -. 
A. x  e.  A  -.  ph )
12 dfrex2 2905 . 2  |-  ( E. y  e.  A  ps  <->  -. 
A. y  e.  A  -.  ps )
1310, 11, 123bitr4i 277 1  |-  ( E. x  e.  A  ph  <->  E. y  e.  A  ps )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    -> wi 4    <-> wb 184   F/wnf 1621   F/_wnfc 2602   A.wral 2804   E.wrex 2805
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1623  ax-4 1636  ax-5 1709  ax-6 1752  ax-7 1795  ax-10 1842  ax-11 1847  ax-12 1859  ax-13 2004  ax-ext 2432
This theorem depends on definitions:  df-bi 185  df-or 368  df-an 369  df-ex 1618  df-nf 1622  df-sb 1745  df-cleq 2446  df-clel 2449  df-nfc 2604  df-ral 2809  df-rex 2810
This theorem is referenced by:  cbvrex  3078  reusv2lem4  4641  reusv2  4643  nnwof  11149  cbviunf  27631  ac6sf2  27687  dfimafnf  27694  aciunf1lem  27729  indexa  30464  evth2f  31630  fvelrnbf  31633  evthf  31642  stoweidlem34  32055  bnj1400  34295
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