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Theorem pm2.13 409
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 116 . 2  |-  ( -. 
ph  ->  -.  -.  -.  ph )
21orri 367 1  |-  ( ph  \/  -.  -.  -.  ph )
Colors of variables: wff set class
Syntax hints:   -. wn 5    \/ wo 359
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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