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Theorem pm4.64 362
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 360 . 2  |-  ( (
ph  \/  ps )  <->  ( -.  ph  ->  ps )
)
21bicomi 194 1  |-  ( ( -.  ph  ->  ps )  <->  (
ph  \/  ps )
)
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    <-> wb 177    \/ wo 358
This theorem is referenced by:  pm4.66  410  ioran  477  fimaxg  7345  kmlem8  8026  axgroth6  8692  dfcon2  17470  hirstL-ax3  27774
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 178  df-or 360
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