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Theorem pm5.62 894
Description: Theorem *5.62 of [WhiteheadRussell] p. 125. (Contributed by Roy F. Longton, 21-Jun-2005.)
Assertion
Ref Expression
pm5.62  |-  ( ( ( ph  /\  ps )  \/  -.  ps )  <->  (
ph  \/  -.  ps )
)

Proof of Theorem pm5.62
StepHypRef Expression
1 exmid 406 . 2  |-  ( ps  \/  -.  ps )
2 ordir 838 . 2  |-  ( ( ( ph  /\  ps )  \/  -.  ps )  <->  ( ( ph  \/  -.  ps )  /\  ( ps  \/  -.  ps )
) )
31, 2mpbiran2 890 1  |-  ( ( ( ph  /\  ps )  \/  -.  ps )  <->  (
ph  \/  -.  ps )
)
Colors of variables: wff set class
Syntax hints:   -. wn 5    <-> wb 178    \/ wo 359    /\ wa 360
This theorem was proved from axioms:  ax-1 7  ax-2 8  ax-3 9  ax-mp 10
This theorem depends on definitions:  df-bi 179  df-or 361  df-an 362
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