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Theorem pm4.64 363
Description: Theorem *4.64 of [WhiteheadRussell] p. 120. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm4.64  |-  ( ( -.  ph  ->  ps )  <->  (
ph  \/  ps )
)

Proof of Theorem pm4.64
StepHypRef Expression
1 df-or 361 . 2  |-  ( (
ph  \/  ps )  <->  ( -.  ph  ->  ps )
)
21bicomi 195 1  |-  ( ( -.  ph  ->  ps )  <->  (
ph  \/  ps )
)
Colors of variables: wff set class
Syntax hints:   -. wn 5    -> wi 6    <-> wb 178    \/ wo 359
This theorem is referenced by:  pm4.66  411  ioran  478  fimaxg  6989  kmlem8  7667  axgroth6  8330  dfcon2  16977  hirstL-ax3  26948
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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