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Theorem truimfal 1355
Description: A  -> identity. (Contributed by Anthony Hart, 22-Oct-2010.) (Proof shortened by Andrew Salmon, 13-May-2011.)
Assertion
Ref Expression
truimfal  |-  ( (  T.  ->  F.  )  <->  F.  )

Proof of Theorem truimfal
StepHypRef Expression
1 tru 1331 . . 3  |-  T.
21a1bi 329 . 2  |-  (  F.  <->  (  T.  ->  F.  )
)
32bicomi 195 1  |-  ( (  T.  ->  F.  )  <->  F.  )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 178    T. wtru 1326    F. wfal 1327
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 179  df-tru 1329
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