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Theorem 19.43 1604
Description: Theorem 19.43 of [Margaris] p. 90. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Wolf Lammen, 27-Jun-2014.)
Assertion
Ref Expression
19.43  |-  ( E. x ( ph  \/  ps )  <->  ( E. x ph  \/  E. x ps ) )

Proof of Theorem 19.43
StepHypRef Expression
1 df-or 361 . . . 4  |-  ( (
ph  \/  ps )  <->  ( -.  ph  ->  ps )
)
21exbii 1580 . . 3  |-  ( E. x ( ph  \/  ps )  <->  E. x ( -. 
ph  ->  ps ) )
3 19.35 1599 . . 3  |-  ( E. x ( -.  ph  ->  ps )  <->  ( A. x  -.  ph  ->  E. x ps ) )
4 alnex 1569 . . . 4  |-  ( A. x  -.  ph  <->  -.  E. x ph )
54imbi1i 317 . . 3  |-  ( ( A. x  -.  ph  ->  E. x ps )  <->  ( -.  E. x ph  ->  E. x ps )
)
62, 3, 53bitri 264 . 2  |-  ( E. x ( ph  \/  ps )  <->  ( -.  E. x ph  ->  E. x ps ) )
7 df-or 361 . 2  |-  ( ( E. x ph  \/  E. x ps )  <->  ( -.  E. x ph  ->  E. x ps ) )
86, 7bitr4i 245 1  |-  ( E. x ( ph  \/  ps )  <->  ( E. x ph  \/  E. x ps ) )
Colors of variables: wff set class
Syntax hints:   -. wn 5    -> wi 6    <-> wb 178    \/ wo 359   A.wal 1532   E.wex 1537
This theorem is referenced by:  19.44  1796  19.45  1797  19.34  1798  rexun  3330  unipr  3815  uniun  3820  unopab  4069  zfpair  4184  dmun  4873  coundi  5161  coundir  5162  kmlem16  7759  vdwapun  12984  pm10.42  26927
This theorem was proved from axioms:  ax-1 7  ax-2 8  ax-3 9  ax-mp 10  ax-5 1533  ax-gen 1536
This theorem depends on definitions:  df-bi 179  df-or 361  df-an 362  df-ex 1538
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