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Theorem falbitruOLD 1479
Description: Obsolete proof of falbitru 1476 as of 10-Jul-2020. (Contributed by Anthony Hart, 22-Oct-2010.) (Proof shortened by Andrew Salmon, 13-May-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
falbitruOLD  |-  ( ( F.  <-> T.  )  <-> F.  )

Proof of Theorem falbitruOLD
StepHypRef Expression
1 bicom 203 . 2  |-  ( ( F.  <-> T.  )  <->  ( T.  <-> F.  ) )
2 trubifal 1477 . 2  |-  ( ( T.  <-> F.  )  <-> F.  )
31, 2bitri 252 1  |-  ( ( F.  <-> T.  )  <-> F.  )
Colors of variables: wff setvar class
Syntax hints:    <-> wb 187   T. wtru 1438   F. wfal 1442
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 188  df-tru 1440
This theorem is referenced by: (None)
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