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Theorem cbvrex2 27918
Description: Change bound variables of double restricted universal quantification, using implicit substitution, analogous to cbvrex2v 2933. (Contributed by Alexander van der Vekens, 2-Jul-2017.)
Hypotheses
Ref Expression
cbvral2.1  |-  F/ z
ph
cbvral2.2  |-  F/ x ch
cbvral2.3  |-  F/ w ch
cbvral2.4  |-  F/ y ps
cbvral2.5  |-  ( x  =  z  ->  ( ph 
<->  ch ) )
cbvral2.6  |-  ( y  =  w  ->  ( ch 
<->  ps ) )
Assertion
Ref Expression
cbvrex2  |-  ( E. x  e.  A  E. y  e.  B  ph  <->  E. z  e.  A  E. w  e.  B  ps )
Distinct variable groups:    x, A    z, A    x, y, B   
y, z, B    w, B
Allowed substitution hints:    ph( x, y, z, w)    ps( x, y, z, w)    ch( x, y, z, w)    A( y, w)

Proof of Theorem cbvrex2
StepHypRef Expression
1 nfcv 2571 . . . 4  |-  F/_ z B
2 cbvral2.1 . . . 4  |-  F/ z
ph
31, 2nfrex 2753 . . 3  |-  F/ z E. y  e.  B  ph
4 nfcv 2571 . . . 4  |-  F/_ x B
5 cbvral2.2 . . . 4  |-  F/ x ch
64, 5nfrex 2753 . . 3  |-  F/ x E. y  e.  B  ch
7 cbvral2.5 . . . 4  |-  ( x  =  z  ->  ( ph 
<->  ch ) )
87rexbidv 2718 . . 3  |-  ( x  =  z  ->  ( E. y  e.  B  ph  <->  E. y  e.  B  ch ) )
93, 6, 8cbvrex 2921 . 2  |-  ( E. x  e.  A  E. y  e.  B  ph  <->  E. z  e.  A  E. y  e.  B  ch )
10 cbvral2.3 . . . 4  |-  F/ w ch
11 cbvral2.4 . . . 4  |-  F/ y ps
12 cbvral2.6 . . . 4  |-  ( y  =  w  ->  ( ch 
<->  ps ) )
1310, 11, 12cbvrex 2921 . . 3  |-  ( E. y  e.  B  ch  <->  E. w  e.  B  ps )
1413rexbii 2722 . 2  |-  ( E. z  e.  A  E. y  e.  B  ch  <->  E. z  e.  A  E. w  e.  B  ps )
159, 14bitri 241 1  |-  ( E. x  e.  A  E. y  e.  B  ph  <->  E. z  e.  A  E. w  e.  B  ps )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 177   F/wnf 1553   E.wrex 2698
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1555  ax-5 1566  ax-17 1626  ax-9 1666  ax-8 1687  ax-6 1744  ax-7 1749  ax-11 1761  ax-12 1950  ax-ext 2416
This theorem depends on definitions:  df-bi 178  df-or 360  df-an 361  df-tru 1328  df-ex 1551  df-nf 1554  df-sb 1659  df-cleq 2428  df-clel 2431  df-nfc 2560  df-ral 2702  df-rex 2703
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