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Theorem biort 867
Description: A wff disjoined with truth is true. (Contributed by NM, 23-May-1999.)
Assertion
Ref Expression
biort  |-  ( ph  ->  ( ph  <->  ( ph  \/  ps ) ) )

Proof of Theorem biort
StepHypRef Expression
1 orc 375 . 2  |-  ( ph  ->  ( ph  \/  ps ) )
2 ax-1 5 . 2  |-  ( ph  ->  ( ( ph  \/  ps )  ->  ph )
)
31, 2impbid2 196 1  |-  ( ph  ->  ( ph  <->  ( ph  \/  ps ) ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 177    \/ wo 358
This theorem is referenced by:  pm5.55  868
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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