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Theorem pm2.68 401
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 157 . 2  |-  ( ( ( ph  ->  ps )  ->  ps )  -> 
( -.  ph  ->  ps ) )
21orrd 369 1  |-  ( ( ( ph  ->  ps )  ->  ps )  -> 
( ph  \/  ps ) )
Colors of variables: wff set class
Syntax hints:    -> wi 6    \/ wo 359
This theorem is referenced by:  dfor2  402
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
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