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Theorem 2rexbiia 2473
Description: Inference adding two restricted existential quantifiers to both sides of an equivalence. (Contributed by NM, 1-Aug-2004.)
Hypothesis
Ref Expression
2rexbiia.1  |-  ( ( x  e.  A  /\  y  e.  B )  ->  ( ph  <->  ps )
)
Assertion
Ref Expression
2rexbiia  |-  ( E. x  e.  A  E. y  e.  B  ph  <->  E. x  e.  A  E. y  e.  B  ps )
Distinct variable groups:    x, y    y, A
Allowed substitution hints:    ph( x, y)    ps( x, y)    A( x)    B( x, y)

Proof of Theorem 2rexbiia
StepHypRef Expression
1 2rexbiia.1 . . 3  |-  ( ( x  e.  A  /\  y  e.  B )  ->  ( ph  <->  ps )
)
21rexbidva 2454 . 2  |-  ( x  e.  A  ->  ( E. y  e.  B  ph  <->  E. y  e.  B  ps ) )
32rexbiia 2472 1  |-  ( E. x  e.  A  E. y  e.  B  ph  <->  E. x  e.  A  E. y  e.  B  ps )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ wa 103    <-> wb 104    e. wcel 2128   E.wrex 2436
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1427  ax-gen 1429  ax-ie1 1473  ax-ie2 1474  ax-4 1490  ax-17 1506  ax-ial 1514
This theorem depends on definitions:  df-bi 116  df-nf 1441  df-rex 2441
This theorem is referenced by:  elq  9531  cnref1o  9559
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