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Theorem tbtru 1380
Description: A proposition is equivalent to itself being equivalent to T.. (Contributed by Anthony Hart, 14-Aug-2011.)
Assertion
Ref Expression
tbtru  |-  ( ph  <->  (
ph 
<-> T.  ) )

Proof of Theorem tbtru
StepHypRef Expression
1 tru 1374 . 2  |- T.
21tbt 344 1  |-  ( ph  <->  (
ph 
<-> T.  ) )
Colors of variables: wff setvar class
Syntax hints:    <-> wb 184   T. wtru 1371
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 185  df-tru 1373
This theorem is referenced by:  sgn3da  27069  aistia  30060
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