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Theorem excomim 1594
Description: One direction of Theorem 19.11 of [Margaris] p. 89. (Contributed by NM, 5-Aug-1993.)
Assertion
Ref Expression
excomim  |-  ( E. x E. y ph  ->  E. y E. x ph )

Proof of Theorem excomim
StepHypRef Expression
1 19.8a 1523 . . 3  |-  ( ph  ->  E. x ph )
212eximi 1533 . 2  |-  ( E. x E. y ph  ->  E. x E. y E. x ph )
3 hbe1 1425 . . . 4  |-  ( E. x ph  ->  A. x E. x ph )
43hbex 1568 . . 3  |-  ( E. y E. x ph  ->  A. x E. y E. x ph )
5419.9h 1575 . 2  |-  ( E. x E. y E. x ph  <->  E. y E. x ph )
62, 5sylib 120 1  |-  ( E. x E. y ph  ->  E. y E. x ph )
Colors of variables: wff set class
Syntax hints:    -> wi 4   E.wex 1422
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-5 1377  ax-7 1378  ax-gen 1379  ax-ie1 1423  ax-ie2 1424  ax-4 1441  ax-ial 1468
This theorem depends on definitions:  df-bi 115
This theorem is referenced by:  excom  1595  2euswapdc  2034
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