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Theorem pm2.68 399
Description: Theorem *2.68 of [WhiteheadRussell] p. 108. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm2.68  |-  ( ( ( ph  ->  ps )  ->  ps )  -> 
( ph  \/  ps ) )

Proof of Theorem pm2.68
StepHypRef Expression
1 jarl 155 . 2  |-  ( ( ( ph  ->  ps )  ->  ps )  -> 
( -.  ph  ->  ps ) )
21orrd 367 1  |-  ( ( ( ph  ->  ps )  ->  ps )  -> 
( ph  \/  ps ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    \/ wo 357
This theorem is referenced by:  dfor2  400
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 177  df-or 359
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