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Theorem 2sbcrex 26780
Description: Exchange an existential quantifier with two substitutions. (Contributed by Stefan O'Rear, 11-Oct-2014.)
Hypotheses
Ref Expression
2sbcrex.1  |-  A  e. 
_V
2sbcrex.2  |-  B  e. 
_V
Assertion
Ref Expression
2sbcrex  |-  ( [. A  /  a ]. [. B  /  b ]. E. c  e.  C  ph  <->  E. c  e.  C  [. A  / 
a ]. [. B  / 
b ]. ph )
Distinct variable groups:    A, c    B, c    C, b    a, c   
b, c    C, a
Allowed substitution hints:    ph( a, b, c)    A( a, b)    B( a, b)    C( c)

Proof of Theorem 2sbcrex
StepHypRef Expression
1 2sbcrex.2 . . . 4  |-  B  e. 
_V
2 sbcrexg 3228 . . . 4  |-  ( B  e.  _V  ->  ( [. B  /  b ]. E. c  e.  C  ph  <->  E. c  e.  C  [. B  /  b ]. ph )
)
31, 2ax-mp 8 . . 3  |-  ( [. B  /  b ]. E. c  e.  C  ph  <->  E. c  e.  C  [. B  / 
b ]. ph )
43sbcbii 3208 . 2  |-  ( [. A  /  a ]. [. B  /  b ]. E. c  e.  C  ph  <->  [. A  / 
a ]. E. c  e.  C  [. B  / 
b ]. ph )
5 2sbcrex.1 . . 3  |-  A  e. 
_V
6 sbcrexg 3228 . . 3  |-  ( A  e.  _V  ->  ( [. A  /  a ]. E. c  e.  C  [. B  /  b ]. ph  <->  E. c  e.  C  [. A  /  a ]. [. B  /  b ]. ph )
)
75, 6ax-mp 8 . 2  |-  ( [. A  /  a ]. E. c  e.  C  [. B  /  b ]. ph  <->  E. c  e.  C  [. A  / 
a ]. [. B  / 
b ]. ph )
84, 7bitri 241 1  |-  ( [. A  /  a ]. [. B  /  b ]. E. c  e.  C  ph  <->  E. c  e.  C  [. A  / 
a ]. [. B  / 
b ]. ph )
Colors of variables: wff set class
Syntax hints:    <-> wb 177    e. wcel 1725   E.wrex 2698   _Vcvv 2948   [.wsbc 3153
This theorem is referenced by:  2rexfrabdioph  26793  4rexfrabdioph  26795
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-clab 2422  df-cleq 2428  df-clel 2431  df-nfc 2560  df-ral 2702  df-rex 2703  df-v 2950  df-sbc 3154
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