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Theorem pm5.5 241
Description: Theorem *5.5 of [WhiteheadRussell] p. 125. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm5.5  |-  ( ph  ->  ( ( ph  ->  ps )  <->  ps ) )

Proof of Theorem pm5.5
StepHypRef Expression
1 biimt 240 . 2  |-  ( ph  ->  ( ps  <->  ( ph  ->  ps ) ) )
21bicomd 140 1  |-  ( ph  ->  ( ( ph  ->  ps )  <->  ps ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 104
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107
This theorem depends on definitions:  df-bi 116
This theorem is referenced by:  imim21b  251  elabgt  2825  sbceqal  2964  dffun8  5154  ordiso2  6923  indstr2  9425  dfgcd2  11725
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