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Theorem pm2.54 364
Description: Theorem *2.54 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm2.54  |-  ( ( -.  ph  ->  ps )  ->  ( ph  \/  ps ) )

Proof of Theorem pm2.54
StepHypRef Expression
1 df-or 360 . 2  |-  ( (
ph  \/  ps )  <->  ( -.  ph  ->  ps )
)
21biimpri 198 1  |-  ( ( -.  ph  ->  ps )  ->  ( ph  \/  ps ) )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    \/ wo 358
This theorem is referenced by:  orrd  368
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8
This theorem depends on definitions:  df-bi 178  df-or 360
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