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Theorem pm4.25 708
Description: Theorem *4.25 of [WhiteheadRussell] p. 117. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm4.25  |-  ( ph  <->  (
ph  \/  ph ) )

Proof of Theorem pm4.25
StepHypRef Expression
1 oridm 707 . 2  |-  ( (
ph  \/  ph )  <->  ph )
21bicomi 130 1  |-  ( ph  <->  (
ph  \/  ph ) )
Colors of variables: wff set class
Syntax hints:    <-> wb 103    \/ wo 662
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 663
This theorem depends on definitions:  df-bi 115
This theorem is referenced by: (None)
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