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Theorem pm2.13 407
Description: Theorem *2.13 of [WhiteheadRussell] p. 101. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm2.13  |-  ( ph  \/  -.  -.  -.  ph )

Proof of Theorem pm2.13
StepHypRef Expression
1 notnot1 114 . 2  |-  ( -. 
ph  ->  -.  -.  -.  ph )
21orri 365 1  |-  ( ph  \/  -.  -.  -.  ph )
Colors of variables: wff set class
Syntax hints:   -. wn 3    \/ wo 357
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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