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Theorem falbitru 1474
Description: A  <-> identity. (Contributed by Anthony Hart, 22-Oct-2010.) (Proof shortened by Andrew Salmon, 13-May-2011.) (Proof shortened by Wolf Lammen, 10-Jul-2020.)
Assertion
Ref Expression
falbitru  |-  ( ( F.  <-> T.  )  <-> F.  )

Proof of Theorem falbitru
StepHypRef Expression
1 tru 1441 . . 3  |- T.
21tbt 345 . 2  |-  ( F.  <-> 
( F.  <-> T.  )
)
32bicomi 205 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:  trubifal  1475  falxortruOLD  1487
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