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Theorem biort 772
Description: A wff is 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 666 . 2  |-  ( ph  ->  ( ph  \/  ps ) )
2 ax-1 5 . 2  |-  ( ph  ->  ( ( ph  \/  ps )  ->  ph )
)
31, 2impbid2 141 1  |-  ( ph  ->  ( ph  <->  ( ph  \/  ps ) ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> 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:  pm5.55dc  853
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