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Theorem pm2.53 364
Description: Theorem *2.53 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm2.53  |-  ( (
ph  \/  ps )  ->  ( -.  ph  ->  ps ) )

Proof of Theorem pm2.53
StepHypRef Expression
1 df-or 361 . 2  |-  ( (
ph  \/  ps )  <->  ( -.  ph  ->  ps )
)
21biimpi 188 1  |-  ( (
ph  \/  ps )  ->  ( -.  ph  ->  ps ) )
Colors of variables: wff set class
Syntax hints:   -. wn 5    -> wi 6    \/ wo 359
This theorem is referenced by:  jaoi  370  orel1  373  pm2.63  766  pm2.8  826  mtp-or  1531  19.33b  1600  soxp  6189  iccpnfcnv  18436  expdioph  26515  pm10.57  26965  stoweidlem39  27187  vk15.4j  27562  vk15.4jVD  27958
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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