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Theorem 19.2 1759
Description: Theorem 19.2 of [Margaris] p. 89, generalized to use two set variables. (Contributed by O'Cat, 31-Mar-2008.)
Assertion
Ref Expression
19.2  |-  ( A. x ph  ->  E. y ph )

Proof of Theorem 19.2
StepHypRef Expression
1 19.8a 1758 . 2  |-  ( ph  ->  E. y ph )
21a4s 1700 1  |-  ( A. x ph  ->  E. y ph )
Colors of variables: wff set class
Syntax hints:    -> wi 6   A.wal 1532   E.wex 1537
This theorem is referenced by:  19.39  1792  19.24  1793  19.34  1798  eusv2i  4504  extt  24220  pm10.251  26924  a9e2eq  27468  a9e2eqVD  27825
This theorem was proved from axioms:  ax-1 7  ax-2 8  ax-3 9  ax-mp 10  ax-4 1692
This theorem depends on definitions:  df-bi 179  df-ex 1538
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